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Title: Dry-Farming
Author: John A. Widtsoe
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*** START OF THE PROJECT GUTENBERG EBOOK, DRY-FARMING ***
Edited by Charles Aldarondo (aldarondo@yahoo.com).
DRY-FARMING
A SYSTEM OF AGRICULTURE FOR COUNTRIES UNDER LOW RAINFALL
BY JOHN A. WIDTSOE, A.M., Ph. D
PRESIDENT OF THE AGRICULTURAL COLLEGE OF UTAH
NEW YORK
1920
TO
LEAH
THIS BOOK IS INSCRIBED
JUNE 1, 1910
PREFACE
Nearly six tenths of the earth's land surface receive an annual
rainfall of less than twenty inches, and can be reclaimed for
agricultural purposes only by irrigation and dry-farming. A
perfected world-system of irrigation will convert about one tenth of
this vast area into an incomparably fruitful garden, leaving about
one half of the earth's land surface to be reclaimed, if at all, by
the methods of dry-farming. The noble system of modern agriculture
has been constructed almost wholly in countries of abundant
rainfall, and its applications are those demanded for the
agricultural development of humid regions. Until recently irrigation
was given scant attention, and dry-farming, with its world problem
of conquering one half of the earth, was not considered. These facts
furnish the apology for the writing of this book.
One volume, only, in this world of many books, and that less than a
year old, is devoted to the exposition of the accepted dry-farm
practices of to-day.
The book now offered is the first attempt to assemble and organize
the known facts of science in their relation to the production of
plants, without irrigation, in regions of limited rainfall. The
needs of the actual farmer, who must understand the principles
before his practices can be wholly satisfactory, have been kept in
view primarily; but it is hoped that the enlarging group of dry-farm
investigators will also be helped by this presentation of the
principles of dry-farming. The subject is now growing so rapidly
that there will soon be room for two classes of treatment: one for
the farmer, and one for the technical student.
This book has been written far from large libraries, and the
material has been drawn from the available sources. Specific
references are not given in the text, but the names of investigators
or institutions are found with nearly all statements of fact. The
files of the Experiment Station Record and Der Jahresbericht der
Agrikultur Chemie have taken the place of the more desirable
original publications. Free use has been made of the publications of
the experiment stations and the United States Department of
Agriculture. Inspiration and suggestions have been sought and found
constantly in the works of the princes of American soil
investigation, Hilgard of California and King of Wisconsin. I am
under deep obligation, for assistance rendered, to numerous friends
in all parts of the country, especially to Professor L. A. Merrill,
with whom I have collaborated for many years in the study of the
possibilities of dry-farming in Western America.
The possibilities of dry-farming are stupendous. In the strength of
youth we may have felt envious of the great ones of old; of Columbus
looking upon the shadow of the greatest continent; of Balboa
shouting greetings to the resting Pacific; of Father Escalante,
pondering upon the mystery of the world, alone, near the shores of
America's Dead Sea. We need harbor no such envyings, for in the
conquest of the nonirrigated and nonirrigable desert are offered as
fine opportunities as the world has known to the makers and shakers
of empires. We stand before an undiscovered land; through the
restless, ascending currents of heated desert air the vision comes
and goes. With striving eyes the desert is seen covered with
blossoming fields, with churches and homes and schools, and, in the
distance, with the vision is heard the laughter of happy children.
The desert will be conquered.
JOHN A. WIDTSOE.
June 1, 1910.
CHAPTER I
INTRODUCTION
DRY-FARMING DEFINED
Dry-farming, as at present understood, is the profitable production
of useful crops, without irrigation, on lands that receive annually
a rainfall of 20 inches or less. In districts of torrential rains,
high winds, unfavorable distribution of the rainfall, or other
water-dissipating factors, the term "dry-farming" is also properly
applied to farming without irrigation under an annual precipitation
of 25 or even 30 inches. There is no sharp demarcation between
dry-and humid-farming.
When the annual precipitation is under 20 inches, the methods of
dry-farming are usually indispensable. When it is over 30 inches,
the methods of humid-farming are employed; in places where the
annual precipitation is between 20 and 30 inches, the methods to be
used depend chiefly on local conditions affecting the conservation
of soil moisture. Dry-farming, however, always implies farming under
a comparatively small annual rainfall.
The term "dry-farming" is, of course, a misnomer. In reality it is
farming under drier conditions than those prevailing in the
countries in which scientific agriculture originated. Many
suggestions for a better name have been made. "Scientific
agriculture" has-been proposed, but all agriculture should be
scientific, and agriculture without irrigation in an arid country
has no right to lay sole claim to so general a title. "Dry-land
agriculture," which has also been suggested, is no improvement over
"dry-farming," as it is longer and also carries with it the idea of
dryness. Instead of the name "dry-farming" it would, perhaps, be
better to use the names, "arid-farming." "semiarid-farming,"
"humid-farming," and "irrigation-farming," according to the climatic
conditions prevailing in various parts of the world. However, at the
present time the name "dry-farming" is in such general use that it
would seem unwise to suggest any change. It should be used with the
distinct understanding that as far as the word "dry" is concerned it
is a misnomer. When the two words are hyphenated, however, a
compound technical term--"dry-farming"--is secured which has a
meaning of its own, such as we have just defined it to be; and
"dry-farming," therefore, becomes an addition to the lexicon.
Dry-versus humid-farming
Dry-farming, as a distinct branch of agriculture, has for its
purpose the reclamation, for the use of man, of the vast unirrigable
"desert" or "semi-desert" areas of the world, which until recently
were considered hopelessly barren. The great underlying principles
of agriculture are the same the world over, yet the emphasis to be
placed on the different agricultural theories and practices must be
shifted in accordance with regional conditions. The agricultural
problem of first importance in humid regions is the maintenance of
soil fertility; and since modern agriculture was developed almost
wholly under humid conditions, the system of scientific agriculture
has for its central idea the maintenance of soil fertility. In arid
regions, on the other hand, the conservation of the natural water
precipitation for crop production is the important problem; and a
new system of agriculture must therefore be constructed, on the
basis of the old principles, but with the conservation of the
natural precipitation as the central idea. The system of dry-farming
must marshal and organize all the established facts of science for
the better utilization, in plant growth, of a limited rainfall. The
excellent teachings of humid agriculture respecting the maintenance
of soil fertility will be of high value in the development of
dry-farming, and the firm establishment of right methods of
conserving and using the natural precipitation will undoubtedly have
a beneficial effect upon the practice of humid agriculture.
The problems of dry-farming
The dry-farmer, at the outset, should know with comparative accuracy
the annual rainfall over the area that he intends to cultivate. He
must also have a good acquaintance with the nature of the soil, not
only as regards its plant-food content, but as to its power to
receive and retain the water from rain and snow. In fact, a
knowledge of the soil is indispensable in successful dry-farming.
Only by such knowledge of the rainfall and the soil is he able to
adapt the principles outlined in this volume to his special needs.
Since, under dry-farm conditions, water is the limiting factor of
production, the primary problem of dry-farming is the most effective
storage in the soil of the natural precipitation. Only the water,
safely stored in the soil within reach of the roots, can be used in
crop production. Of nearly equal importance is the problem of
keeping the water in the soil until it is needed by plants. During
the growing season, water may be lost from the soil by downward
drainage or by evaporation from the surface. It becomes necessary,
therefore, to determine under what conditions the natural
precipitation stored in the soil moves downward and by what means
surface evaporation may be prevented or regulated. The soil-water,
of real use to plants, is that taken up by the roots and finally
evaporated from the leaves. A large part of the water stored in the
soil is thus used. The methods whereby this direct draft of plants
on the soil-moisture may be regulated are, naturally, of the utmost
importance to the dry-farmer, and they constitute another vital
problem of the science of dry-farming.
The relation of crops to the prevailing conditions of arid lands
offers another group of important dry-farm problems. Some plants use
much less water than others. Some attain maturity quickly, and in
that way become desirable for dry-farming. Still other crops, grown
under humid conditions, may easily be adapted to dry-farming
conditions, if the correct methods are employed, and in a few
seasons may be made valuable dry-farm crops. The individual
characteristics of each crop should be known as they relate
themselves to a low rainfall and arid soils.
After a crop has been chosen, skill and knowledge are needed in the
proper seeding, tillage, and harvesting of the crop. Failures
frequently result from the want of adapting the crop treatment to
arid conditions.
After the crop has been gathered and stored, its proper use is
another problem for the dry-farmer. The composition of dry-farm
crops is different from that of crops grown with an abundance of
water. Usually, dry-farm crops are much more nutritious and
therefore should command a higher price in the markets, or should be
fed to stock in corresponding proportions and combinations.
The fundamental problems of dry-farming are, then, the storage in
the soil of a small annual rainfall; the retention in the soil of
the moisture until it is needed by plants; the prevention of the
direct evaporation of soil-moisture during; the growing season; the
regulation of the amount of water drawn from the soil by plants; the
choice of crops suitable for growth under arid conditions; the
application of suitable crop treatments, and the disposal of
dry-farm products, based upon the superior composition of plants
grown with small amounts of water. Around these fundamental problems
cluster a host of minor, though also important, problems. When the
methods of dry-farming are understood and practiced, the practice is
always successful; but it requires more intelligence, more implicit
obedience to nature's laws, and greater vigilance, than farming in
countries of abundant rainfall.
The chapters that follow will deal almost wholly with the problems
above outlined as they present themselves in the construction of a
rational system of farming without irrigation in countries of
limited rainfall.
CHAPTER II
THE THEORETICAL BASIS OF DRY-FARMING
The confidence with which scientific investigators, familiar with
the arid regions, have attacked the problems of dry-farming rests
largely on the known relationship of the water requirements of
plants to the natural precipitation of rain and snow. It is a most
elementary fact of plant physiology that no plant can live and grow
unless it has at its disposal a sufficient amount of water.
The water used by plants is almost entirely taken from the soil by
the minute root-hairs radiating from the roots. The water thus taken
into the plants is passed upward through the stem to the leaves,
where it is finally evaporated. There is, therefore, a more or less
constant stream of water passing through the plant from the roots to
the leaves.
By various methods it is possible to measure the water thus taken
from the soil. While this process of taking water from the soil is
going on within the plant, a certain amount of soil-moisture is also
lost by direct evaporation from the soil surface. In dry-farm
sections, soil-moisture is lost only by these two methods; for
wherever the rainfall is sufficient to cause drainage from deep
soils, humid conditions prevail.
Water for one pound dry matter
Many experiments have been conducted to determine the amount of
water used in the production of one pound of dry plant substance.
Generally, the method of the experiments has been to grow plants in
large pots containing weighed quantities of soil. As needed, weighed
amounts of water were added to the pots. To determine the loss of
water, the pots were weighed at regular intervals of three days to
one week. At harvest time, the weight of dry matter was carefully
determined for each pot. Since the water lost by the pots was also
known, the pounds of water used for the production of every pound of
dry matter were readily calculated.
The first reliable experiments of the kind were undertaken under
humid conditions in Germany and other European countries. From the
mass of results, some have been selected and presented in the
following table. The work was done by the famous German
investigators, Wollny, Hellriegel, and Sorauer, in the early
eighties of the last century. In every case, the numbers in the
table represent the number of pounds of water used for the
production of one pound of ripened dry substance:
Pounds Of Water For One Pound Of Dry Matter
Wollny Hellreigel Sorauer
Wheat 338 459
Oats 665 376 569
Barley 310 431
Rye 774 353 236
Corn 233
Buckwheat 646 363
Peas 416 273
Horsebeans 282
Red clover 310
Sunflowers 490
Millet 447
It is clear from the above results, obtained in Germany, that the
amount of water required to produce a pound of dry matter is not the
same for all plants, nor is it the same under all conditions for the
same plant. In fact, as will be shown in a later chapter, the water
requirements of any crop depend upon numerous factors, more or less
controllable. The range of the above German results is from 233 to
774 pounds, with an average of about 419 pounds of water for each
pound of dry matter produced.
During the late eighties and early nineties, King conducted
experiments similar to the earlier German experiments, to determine
the water requirements of crops under Wisconsin conditions. A
summary of the results of these extensive and carefully conducted
experiments is as follows:--
Oats 385
Barley 464
Corn 271
Peas 477
Clover 576
Potatoes 385
The figures in the above table, averaging about 446 pounds, indicate
that very nearly the same quantity of water is required for the
production of crops in Wisconsin as in Germany. The Wisconsin
results tend to be somewhat higher than those obtained in Europe,
but the difference is small.
It is a settled principle of science, as will be more fully
discussed later, that the amount of water evaporated from the soil
and transpired by plant leaves increases materially with an increase
in the average temperature during the growing season, and is much
higher under a clear sky and in districts where the atmosphere is
dry. Wherever dry-farming is likely to be practiced, a moderately
high temperature, a cloudless sky, and a dry atmosphere are the
prevailing conditions. It appeared probable therefore, that in arid
countries the amount of water required for the production of one
pound of dry matter would be higher than in the humid regions of
Germany and Wisconsin. To secure information on this subject,
Widtsoe and Merrill undertook, in 1900, a series of experiments in
Utah, which were conducted upon the plan of the earlier
experimenters. An average statement of the results of six years'
experimentation is given in the subjoined table, showing the number
of pounds of water required for one pound of dry matter on fertile
soils:--
Wheat 1048
Corn 589
Peas 1118
Sugar Beets 630
These Utah findings support strongly the doctrine that the amount of
water required for the production of each pound of dry matter is
very much larger under arid conditions, as in Utah, than under humid
conditions, as in Germany or Wisconsin. It must be observed,
however, that in all of these experiments the plants were supplied
with water in a somewhat wasteful manner; that is, they were given
an abundance of water, and used the largest quantity possible under
the prevailing conditions. No attempt of any kind was made to
economize water. The results, therefore, represent maximum results
and can be safely used as such. Moreover, the methods of
dry-farming, involving the storage of water in deep soils and
systematic cultivation, were not employed. The experiments, both in
Europe and America, rather represent irrigated conditions. There are
good reasons for believing that in Germany, Wisconsin, and Utah the
amounts above given can be materially reduced by the employment of
proper cultural methods.
The water in the large bottle would be required to produce the grain
in the small bottle.
In view of these findings concerning the water requirements of
crops, it cannot be far from the truth to say that, under average
cultural conditions, approximately 750 pounds of water are required
in an arid district for the production of one pound of dry matter.
Where the aridity is intense, this figure may be somewhat low, and
in localities of sub-humid conditions, it will undoubtedly be too
high. As a maximum average, however, for districts interested in
dry-farming, it can be used with safety.
Crop-producing power of rainfall
If this conclusion, that not more than 750 pounds of water are
required under ordinary dry-farm conditions for the production of
one pound of dry matter, be accepted, certain interesting
calculations can be made respecting the possibilities of
dry-farming. For example, the production of one bushel of wheat will
require 60 times 750, or 45,000 pounds of water. The wheat kernels,
however, cannot be produced without a certain amount of straw, which
under conditions of dry-farming seldom forms quite one half of the
weight of the whole plant. Let us say, however, that the weights of
straw and kernels are equal. Then, to produce one bushel of wheat,
with the corresponding quantity of straw, would require 2 times
45,000, or 90,000 pounds of water. This is equal to 45 tons of water
for each bushel of wheat. While this is a large figure, yet, in many
localities, it is undoubtedly well within the truth. In comparison
with the amounts of water that fall upon the land as rain, it does
not seem extraordinarily large.
One inch of water over one acre of land weighs approximately 226,875
pounds. or over 113 tons. If this quantity of water could be stored
in the soil and used wholly for plant production, it would produce,
at the rate of 45 tons of water for each bushel, about 2-1/2 bushels
of wheat. With 10 inches of rainfall, which up to the present seems
to be the lower limit of successful dry-farming, there is a maximum
possibility of producing 25 bushels of wheat annually.
In the subjoined table, constructed on the basis of the discussion
of this chapter, the wheat-producing powers of various degrees of
annual precipitation are shown:--
One acre inch of water will produce 2-1/2 bushels of wheat.
Ten acre inches of water will produce 25 bushels of wheat.
Fifteen acre inches of water will produce 37-1/2 bushels of wheat.
Twenty acre inches of water will produce 50 bushels of wheat.
It must be distinctly remembered, however, that under no known
system of tillage can all the water that falls upon a soil be
brought into the soil and stored there for plant use. Neither is it
possible to treat a soil so that all the stored soil-moisture may be
used for plant production. Some moisture, of necessity, will
evaporate directly from the soil, and some may be lost in many other
ways. Yet, even under a rainfall of 12 inches, if only one half of
the water can be conserved, which experiments have shown to be very
feasible, there is a possibility of producing 30 bushels of wheat
per acre every other year, which insures an excellent interest on
the money and labor invested in the production of the crop.
It is on the grounds outlined in this chapter that students of the
subject believe that ultimately large areas of the "desert" may be
reclaimed by means of dry-farming. The real question before the
dry-farmer is not, "Is the rainfall sufficient?" but rather, "Is it
possible so to conserve and use the rainfall as to make it available
for the production of profitable crops?"
CHAPTER III
DRY-FARM AREAS--RAINFALL
The annual precipitation of rain and snow determines primarily the
location of dry-farm areas. As the rainfall varies, the methods of
dry-farming must be varied accordingly. Rainfall, alone, does not,
however, furnish a complete index of the crop-producing
possibilities of a country.
The distribution of the rainfall, the amount of snow, the
water-holding power of the soil, and the various
moisture-dissipating causes, such as winds, high temperature,
abundant sunshine, and low humidity frequently combine to offset the
benefits of a large annual precipitation. Nevertheless, no one
climatic feature represents, on the average, so correctly
dry-farming possibilities as does the annual rainfall. Experience
has already demonstrated that wherever the annual precipitation is
above 15 inches, there is no need of crop failures, if the soils are
suitable and the methods of dry-farming are correctly employed. With
an annual precipitation of 10 to 15 inches, there need be very few
failures, if proper cultural precautions are taken. With our present
methods, the areas that receive less than 10 inches of atmospheric
precipitation per year are not safe for dry-farm purposes. What the
future will show in the reclamation of these deserts, without
irrigation, is yet conjectural.
Arid, semiarid, and sub-humid
Before proceeding to an examination of the areas in the United
States subject to the methods of dry-farming it may be well to
define somewhat more clearly the terms ordinarily used in the
description of the great territory involved in the discussion.
The states lying west of the 100th meridian are loosely spoken of as
arid, semiarid, or sub-humid states. For commercial purposes no
state wants to be classed as arid and to suffer under the handicap
of advertised aridity. The annual rainfall of these states ranges
from about 3 to over 30 inches.
In order to arrive at greater definiteness, it may be well to assign
definite rainfall values to the ordinarily used descriptive terms of
the region in question. It is proposed, therefore, that districts
receiving less than 10 inches of atmospheric precipitation annually,
be designated arid; those receiving between 10 and 20 inches,
semiarid; those receiving between 20 and 30 inches, sub-humid, and
those receiving over 30 inches, humid. It is admitted that even such
a classification is arbitrary, since aridity does not alone depend
upon the rainfall, and even under such a classification there is an
unavoidable overlapping. However, no one factor so fully represents
varying degrees of aridity as the annual precipitation, and there is
a great need for concise definitions of the terms used in describing
the parts of the country that come under dry-farming discussions. In
this volume, the terms "arid," "semiarid," "sub-humid" and "humid"
are used as above defined.
Precipitation over the dry-farm territory
Nearly one half of the United States receives 20 inches or less
rainfall annually; and that when the strip receiving between 20 and
30 inches is added, the whole area directly subject to reclamation
by irrigation or dry-farming is considerably more than one half (63
per cent) of the whole area of the United States.
Eighteen states are included in this area of low rainfall. The areas
of these, as given by the Census of 1900, grouped according to the
annual precipitation received, are shown below:--
Arid to Semi-arid Group
Total Area Land Surface (Sq. Miles)
Arizona 112,920
California 156,172
Colorado 103,645
Idaho 84,290
Nevada 109,740
Utah 82,190
Wyoming 97,545
TOTAL 746,532
Semiarid to Sub-Humid Group
Montana 145,310
Nebraska 76,840
New Mexico 112,460
North Dakota 70,195
Oregon 94,560
South Dakota 76,850
Washington 66,880
TOTAL 653,095
Sub-Humid to Humid Group
Kansas 81,700
Minnesota 79,205
Oklahoma 38,830
Texas 262,290
TOTAL 462,025
GRAND TOTAL 1,861,652
The territory directly interested in the development of the methods
of dry-farming forms 63 per cent of the whole of the continental
United States, not including Alaska, and covers an area of 1,861,652
square miles, or 1,191,457,280 acres. If any excuse were needed for
the lively interest taken in the subject of dry-farming, it is amply
furnished by these figures showing the vast extent of the country
interested in the reclamation of land by the methods of dry-farming.
As will be shown below, nearly every other large country possesses
similar immense areas under limited rainfall.
Of the one billion, one hundred and ninety-one million, four hundred
and fifty-seven thousand, two hundred and eighty acres
(1,191,457,280) representing the dry-farm territory of the United
States, about 22 per cent, or a little more than one fifth, is
sub-humid and receives between 20 and 30 inches of rainfall,
annually; 61 per cent, or a little more than three fifths, is
semiarid and receives between 10 and 20 inches, annually, and about
17 per cent, or a little less than one fifth, is arid and receives
less than 10 inches of rainfall, annually.
These calculations are based upon the published average rainfall
maps of the United States Weather Bureau. In the far West, and
especially over the so-called "desert" regions, with their sparse
population, meteorological stations are not numerous, nor is it easy
to secure accurate data from them. It is strongly probable that as
more stations are established, it will be found that the area
receiving less than 10 inches of rainfall annually is considerably
smaller than above estimated. In fact, the United States Reclamation
Service states that there are only 70,000,000 acres of desert-like
land; that is, land which does not naturally support plants suitable
for forage. This area is about one third of the lands which, so far
as known, at present receive less than 10 inches of rainfall, or
only about 6 per cent of the total dry-farming territory.
In any case, the semiarid area is at present most vitally interested
in dry-farming. The sub-humid area need seldom suffer from drouth,
if ordinary well-known methods are employed; the arid area,
receiving less than 10 inches of rainfall, in all probability, can
be reclaimed without irrigation only by the development of more
suitable. methods than are known to-day. The semiarid area, which is
the special consideration of present-day dry-farming represents an
area of over 725,000,000 acres of land. Moreover, it must be
remarked that the full certainty of crops in the sub-humid regions
will come only with the adoption of dry-farming methods; and that
results already obtained on the edge of the "deserts" lead to the
belief that a large portion of the area receiving less than 10
inches of rainfall, annually, will ultimately be reclaimed without
irrigation.
Naturally, not the whole of the vast area just discussed could be
brought under cultivation, even under the most favorable conditions
of rainfall. A very large portion of the territory in question is
mountainous and often of so rugged a nature that to farm it would be
an impossibility. It must not be forgotten, however, that some of
the best dry-farm lands of the West are found in the small mountain
valleys, which usually are pockets of most fertile soil, under a
good supply of rainfall. The foothills of the mountains are almost
invariably excellent dry-farm lands. Newell estimates that
195,000,000 acres of land in the arid to sub-humid sections are
covered with a more or less dense growth of timber. This timbered
area roughly represents the mountainous and therefore the nonarable
portions of land. The same authority estimates that the desert-like
lands cover an area of 70,000,000 acres. Making the most liberal
estimates for mountainous and desert-like lands, at least one half
of the whole area, or about 600,000,000 acres, is arable land which
by proper methods may be reclaimed for agricultural purposes.
Irrigation when fully developed may reclaim not to exceed 5 per cent
of this area. From any point of view, therefore, the possibilities
involved in dry-farming in the United States are immense.
Dry-farm area of the world
Dry-farming is a world problem. Aridity is a condition met and to be
overcome upon every continent. McColl estimates that in Australia,
which is somewhat larger than the continental United States of
America, only one third of the whole surface receives above 20
inches of rainfall annually; one third receives from 10 to 20
inches, and one third receives less than lO inches. That is, about
1,267,000,000 acres in Australia are subject to reclamation by
dry-farming methods. This condition is not far from that which
prevails in the United States, and is representative of every
continent of the world. The following table gives the proportions of
the earth's land surface under various degrees of annual
precipitations:--
Annual Precipitation Proportion of Earth's Land Surface
Under 10 inches 25.0 per cent
From 10 to 20 inches 30.0 per cent
From 20 to 40 inches 20.0 per cent
From 40 to 60 inches 11.0 per cent
From 60 to 80 inches 9.0 per cent
From 100 to 120 inches 4.0 per cent
From 120 to 160 inches 0.5 per cent
Above 160 inches 0.5 per cent
Total 100 per cent
Fifty-five per cent, or more than one half of the total land surface
of the earth, receives an annual precipitation of less than 20
inches, and must be reclaimed, if at all, by dry-farming. At least
10 per cent more receives from 20 to 30 inches under conditions that
make dry-farming methods necessary. A total of about 65 per cent of
the earth's land surface is, therefore, directly interested in
dry-farming. With the future perfected development of irrigation
systems and practices, not more than 10 per cent will be reclaimed
by irrigation. Dry-farming is truly a problem to challenge the
attention of the race.
CHAPTER IV
DRY-FARM AREAS.--GENERAL CLIMATIC FEATURES
The dry-farm territory of the United States stretches from the
Pacific seaboard to the 96th parallel of longitude, and from the
Canadian to the Mexican boundary, making a total area of nearly
1,800,000 square miles. This immense territory is far from being a
vast level plain. On the extreme east is the Great Plains region of
the Mississippi Valley which is a comparatively uniform country of
rolling hills, but no mountains. At a point about one third of the
whole distance westward the whole land is lifted skyward by the
Rocky Mountains, which cross the country from south to northwest.
Here are innumerable peaks, canons, high table-lands, roaring
torrents, and quiet mountain valleys. West of the Rockies is the
great depression known as the Great Basin, which has no outlet to
the ocean. It is essentially a gigantic level lake floor traversed
in many directions by mountain ranges that are offshoots from the
backbone of the Rockies. South of the Great Basin are the high
plateaus, into which many great chasms are cut, the best known and
largest of which is the great Canon of the Colorado. North and east
of the Great Basin is the Columbia River Basin characterized by
basaltic rolling plains and broken mountain country. To the west,
the floor of the Great Basin is lifted up into the region of eternal
snow by the Sierra Nevada Mountains, which north of Nevada are known
as the Cascades. On the west, the Sierra Nevadas slope gently,
through intervening valleys and minor mountain ranges, into the
Pacific Ocean. It would be difficult to imagine a more diversified
topography than is possessed by the dry-farm territory of the United
States.
Uniform climatic conditions are not to be expected over such a
broken country. The chief determining factors of climate--latitude,
relative distribution of land and water, elevation, prevailing
winds--swing between such large extremes that of necessity the
climatic conditions of different sections are widely divergent.
Dry-farming is so intimately related to climate that the typical
climatic variations must be pointed out.
The total annual precipitation is directly influenced by the land
topography, especially by the great mountain ranges. On the east of
the Rocky Mountains is the sub-humid district, which receives from
20 to 30 inches of rainfall annually; over the Rockies themselves,
semiarid conditions prevail; in the Great Basin, hemmed in by the
Rockies on the east and the Sierra Nevadas on the west, more arid
conditions predominate; to the west, over the Sierras and down to
the seacoast, semiarid to sub-humid conditions are again found.
Seasonal distribution of rainfall
It is doubtless true that the total annual precipitation is the
chief factor in determining the success of dry-farming. However, the
distribution of the rainfall throughout the year is also of great
importance, and should be known by the farmer. A small rainfall,
coming at the most desirable season, will have greater
crop-producing power than a very much larger rainfall poorly
distributed. Moreover, the methods of tillage to be employed where
most of the precipitation comes in winter must be considerably
different from those used where the bulk of the precipitation comes
in the summer. The successful dry-farmer must know the average
annual precipitation, and also the average seasonal distribution of
the rainfall, over the land which he intends to dry-farm before he
can safely choose his cultural methods.
With reference to the monthly distribution of the precipitation over
the dry-farm territory of the United States, Henry of the United
States Weather Bureau recognizes five distinct types; namely: (1)
Pacific, (2) Sub-Pacific, (3) Arizona, (4) the Northern Rocky
Mountain and Eastern Foothills, and (5) the Plains Type:--
_"The Pacific Type.--_This type is found in all of the territory
west of the Cascade and Sierra Nevada ranges, and also obtains in a
fringe of country to the eastward of the mountain summits. The
distinguishing characteristic of the Pacific type is a wet season,
extending from October to March, and a practically rainless summer,
except in northern California and parts of Oregon and Washington.
About half of the yearly precipitation comes in the months of
December, January, and February, the remaining half being
distributed throughout the seven months--September, October,
November, March, April, May, and June."
_"Sub-Pacific Type.--_The term 'Sub-Pacific' has been given to that
type of rainfall which obtains over eastern Washington, Nevada, and
Utah. The influences that control the precipitation of this region
are much similar to those that prevail west of the Sierra Nevada and
Cascade ranges. There is not, however, as in the eastern type, a
steady diminution in the precipitation with the approach of spring,
but rather a culmination in the precipitation."
_"Arizona Type.--_The Arizona Type, so called because it is more
fully developed in that territory than elsewhere, prevails over
Arizona, New Mexico, and a small portion of eastern Utah and Nevada.
This type differs from all others in the fact that about 35 per cent
of the rain falls in July and August. May and June are generally the
months of least rainfall."
_"The Northern Rocky Mountain and Eastern Foothills Type.--_This
type is closely allied to that of the plains to the eastward, and
the bulk of the rain falls in the foothills of the region in April
and May; in Montana, in May and June."
_"The Plains Type.--_This type embraces the greater part of the
Dakotas, Nebraska, Kansas; Oklahoma, the Panhandle of Texas, and all
the great corn and wheat states of the interior valleys. This region
is characterized by a scant winter precipitation over the northern
states and moderately heavy rains during the growing season. The.
bulk of the rains comes in May, June, and July."
This classification emphasizes the great variation in distribution
of rainfall over the dry-farm territory of the country. West of the
Rocky Mountains the precipitation comes chiefly in winter and
spring, leaving the summers rainless; while east of the Rockies, the
winters are somewhat rainless and the precipitation comes chiefly in
spring and summer. The Arizona type stands midway between these
types. This variation in the distribution of the rainfall requires
that different methods be employed in storing and conserving the
rainfall for crop production. The adaptation of cultural methods to
the seasonal distribution of rainfall will be discussed hereafter.
Snowfall
Closely related to the distribution of the rainfall and the average
annual temperature is the snowfall. Wherever a relatively large
winter precipitation occurs, the dry-farmer is benefited if it comes
in the form of snow. The fall-planted seeds are better protected by
the snow; the evaporation is lower and it appears that the soil is
improved by the annual covering of snow. In any case, the methods of
culture are in a measure dependent upon the amount of snowfall and
the length of time that it lies upon the ground.
Snow falls over most of the dry-farm territory, excepting the
lowlands of California, the immediate Pacific coast, and other
districts where the average annual temperature is high. The heaviest
snowfall is in the intermountain district, from the west slope of
the Sierra Nevadas to the east slope of the Rockies. The degree of
snowfall on the agricultural lands is very variable and dependent
upon local conditions. Snow falls upon all the high mountain ranges.
Temperature
With the exceptions of portions of California, Arizona, and Texas
the average annual surface temperature of the dry-farm territory of
the United States ranges from 40 deg to 55 deg F. The average is not
far from 45 deg F. This places most of the dry-farm territory in the
class of cold regions, though a small area on the extreme east
border may be classed as temperate, and parts of California and
Arizona as warm. The range in temperature from the highest in summer
to the lowest in winter is considerable, but not widely different
from other similar parts of the United States. The range is greatest
in the interior mountainous districts, and lowest along the
seacoast. The daily range of the highest and lowest temperatures for
any one day is generally higher over dry-farm sections than over
humid districts. In the Plateau regions of the semiarid country the
average daily variation is from 30 to 35 deg F., while east of the
Mississippi it is only about 20 deg F. This greater daily range is
chiefly due to the clear skies and scant vegetation which facilitate
excessive warming by day and cooling by night.
The important temperature question for the dry-farmer is whether the
growing season is sufficiently warm and long to permit the maturing
of crops. There are few places, even at high altitudes in the region
considered, where the summer temperature is so low as to retard the
growth of plants. Likewise, the first and last killing frosts are
ordinarily so far apart as to allow an ample growing season. It must
be remembered that frosts are governed very largely by local
topographic features, and must be known from a local point of view.
It is a general law that frosts are more likely to occur in valleys
than on hillsides, owing to the downward drainage of the cooled air.
Further, the danger of frost increases with the altitude. In
general, the last killing frost in spring over the dry-farm
territory varies from March 15 to May 29, and the first killing
frost in autumn from September 15 to November 15. These limits
permit of the maturing of all ordinary farm crops, especially the
grain crops.
Relative humidity
At a definite temperature, the atmosphere can hold only a certain
amount of water vapor. When the air can hold no more, it is said to
be saturated. When it is not saturated, the amount of water vapor
actually held by the air is expressed in percentages of the quantity
required for saturation. A relative humidity of 100 per cent means
that the air is saturated; of 50 per cent, that it is only one half
saturated. The drier the air is, the more rapidly does the water
evaporate into it. To the dry-farmer, therefore, the relative
humidity or degree of dryness of the air is of very great
importance. According to Professor Henry, the chief characteristics
of the geographic distribution of relative humidity in the United
States are as follows:--
(1) Along the coasts there is a belt of high humidity at all
seasons, the percentage of saturation ranging from 75 to 80 per
cent.
(2) Inland, from about the 70th meridian eastward to the Atlantic
coast, the amount varies between 70 and 75 per cent.
(3) The dry region is in the Southwest, where the average annual
value is not over 50 per cent. In this region are included Arizona,
New Mexico, western Colorado, and the greater portion of both Utah
and Nevada. The amount of annual relative humidity in the remaining
portion of the elevated district, between the 100th meridian on the
east to the Sierra Nevada and the Cascades on the west, varies
between 55 and 65 per cent. In July, August, and September, the mean
values in the Southwest sink as low as 20 to 30 per cent, while
along the Pacific coast districts they continue about 80 per cent
the year round. In the Atlantic coast districts, and generally east
from the Mississippi River, the variation from month to month is not
great. April is probably the driest month of the year.
The air of the dry-farm territory, therefore, on the whole, contains
considerably less than two thirds the amount of moisture carried by
the air of the humid states. This means that evaporation from plant
leaves and soil surfaces will go on more rapidly in semiarid than in
humid regions. Against this danger, which cannot he controlled, the
dry-farmer must take special precautions.
Sunshine
The amount of sunshine in a dry-farm section is also of importance.
Direct sunshine promotes plant growth, but at the same time it
accelerates the evaporation of water from the soil. The whole
dry-farm territory receives more sunshine than do the humid
sections. In fact, the amount of sunshine may roughly be said to
increase as the annual rainfall decreases. Over the larger part of
the arid and semiarid sections the sun shines over 70 per cent of
the time.
Winds
The winds of any locality, owing to their moisture-dissipating
power play an important part in the success of dry-farming. A
persistent wind will offset much of the benefit of a heavy rainfall
and careful cultivation. While great general laws have been
formulated regarding the movements of the atmosphere, they are of
minor value in judging the effect of wind on any farming district.
Local observations, however, may enable the farmer to estimate the
probable effect of the winds and thus to formulate proper cultural
means of protection. In general, those living in a district are able
to describe it without special observations as windy or quiet. In
the dry-farm territory of the United States the one great region of
relatively high and persistent winds is the Great Plains region east
of the Rocky Mountains. Dry-farmers in that section will of
necessity be obliged to adopt cultural methods that will prevent the
excessive evaporation naturally induced by the unhindered wind, and
the possible blowing of well-tilled fallow land.
Summary
The dry-farm territory is characterized by a low rainfall, averaging
between 10 and 20 inches, the distribution of which falls into two
distinct types: a heavy winter and spring with a light summer
precipitation, and a heavy spring and summer with a light winter
precipitation. Snow falls over most of the territory, but does not
lie long outside of the mountain states. The whole dry-farm
territory may be classed as temperate to cold; relatively high and
persistent winds blow only over the Great Plains, though local
conditions cause strong regular winds in many other places; the air
is dry and the sunshine is very abundant. In brief, little water
falls upon the dry-farm territory, and the climatic factors are of a
nature to cause rapid evaporation.
In view of this knowledge, it is not surprising that thousands of
farmers, employing, often carelessly agricultural methods developed
in humid sections, have found only hardships and poverty on the
present dry-farm empire of the United States.
Drouth
Drouth is said to be the arch enemy of the dry-farmer, but few agree
upon its meaning. For the purposes of this volume, drouth may be
defined as a condition under which crops fail to mature because of
an insufficient supply of water. Providence has generally been
charged with causing drouths, but under the above definition, man is
usually the cause. Occasionally, relatively dry years occur, but
they are seldom dry enough to cause crop failures if proper methods
of farming have been practiced. There are four chief causes of
drouth: (1) Improper or careless preparation of the soil; (2)
failure to store the natural precipitation in the soil; (3) failure
to apply proper cultural methods for keeping the moisture in the
soil until needed by plants, and (4) sowing too much seed for the
available soil-moisture.
Crop failures due to untimely frosts, blizzards, cyclones,
tornadoes, or hail may perhaps be charged to Providence, but the
dry-farmer must accept the responsibility for any crop injury
resulting from drouth. A fairly accurate knowledge of the climatic
conditions of the district, a good understanding of the principles
of agriculture without irrigation under a low rainfall, and a
vigorous application of these principles as adapted to the local
climatic conditions will make dry-farm failures a rarity.
CHAPTER V
DRY-FARM SOILS
Important as is the rainfall in making dry-farming successful, it is
not more so than the soils of the dry-farms. On a shallow soil, or
on one penetrated with gravel streaks, crop failures are probable
even under a large rainfall; but a deep soil of uniform texture,
unbroken by gravel or hardpan, in which much water may be stored,
and which furnishes also an abundance of feeding space for the
roots, will yield large crops even under a very small rainfall.
Likewise, an infertile soil, though it be deep, and under a large
precipitation, cannot be depended on for good crops; but a fertile
soil, though not quite so deep, nor under so large a rainfall, will
almost invariably bring large crops to maturity.
A correct understanding of the soil, from the surface to a depth of
ten feet, is almost indispensable before a safe Judgment can be
pronounced upon the full dry-farm possibilities of a district.
Especially is it necessary to know (a) the depth, (b) the uniformity
of structure, and (c) the relative fertility of the soil, in order
to plan an intelligent system of farming that will be rationally
adapted to the rainfall and other climatic factors.
It is a matter of regret that so much of our information concerning
the soils of the dry-farm territory of the United States and other
countries has been obtained according to the methods and for the
needs of humid countries, and that, therefore, the special knowledge
of our arid and semiarid soils needed for the development of
dry-farming is small and fragmentary. What is known to-day
concerning the nature of arid soils and their relation to cultural
processes under a scanty rainfall is due very largely to the
extensive researches and voluminous writings of Dr. E. W. Hilgard,
who for a generation was in charge of the agricultural work of the
state of California. Future students of arid soils must of necessity
rest their investigations upon the pioneer work done by Dr. Hilgard.
The contents of this chapter are in a large part gathered from
Hilgard's writings.
The formation of soils
"Soil is the more or less loose and friable material in which, by
means of their roots, plants may or do find a foothold and
nourishment, as well as other conditions of growth." Soil is formed
by a complex process, broadly known as _weathering, _from the rocks
which constitute the earth's crust. Soil is in fact only pulverized
and altered rock. The forces that produce soil from rocks are of two
distinct classes, _physical and chemical. _The physical agencies of
soil production merely cause a pulverization of the rock; the
chemical agencies, on the other hand, so thoroughly change the
essential nature of the soil particles that they are no longer like
the rock from which they were formed.
Of the physical agencies, _temperature changes _are first in order
of time, and perhaps of first importance. As the heat of the day
increases, the rock expands, and as the cold night approaches,
contracts. This alternate expansion and contraction, in time, cracks
the surfaces of the rocks. Into the tiny crevices thus formed water
enters from the falling snow or rain. When winter comes, the water
in these cracks freezes to ice, and in so doing expands and widens
each of the cracks. As these processes are repeated from day to day,
from year to year, and from generation to generation, the surfaces
of the rocks crumble. The smaller rocks so formed are acted upon by
the same agencies, in the same manner, and thus the process of
pulverization goes on.
It is clear, then, that the second great agency of soil formation,
which always acts in conjunction with temperature changes, is
_freezing water. _The rock particles formed in this manner are often
washed down into the mountain valleys, there caught by great rivers,
ground into finer dust, and at length deposited in the lower
valleys. _Moving water _thus becomes another physical agency of soil
production. Most of the soils covering the great dry-farm territory
of the United States and other countries have been formed in this
way.
In places, glaciers moving slowly down the canons crush and grind
into powder the rock over which they pass and deposit it lower down
as soils. In other places, where strong winds blow with frequent
regularity, sharp soil grains are picked up by the air and hurled
against the rocks, which, under this action, are carved into
fantastic forms. In still other places, the strong winds carry soil
over long distances to be mixed with other soils. Finally, on the
seashore the great waves dashing against the rocks of the coast
line, and rolling the mass of pebbles back and forth, break and
pulverize the rock until soil is formed._ Glaciers, winds, _and
_waves _are also, therefore, physical agencies of soil formation.
It may be noted that the result of the action of all these agencies
is to form a rock powder, each particle of which preserves the
composition that it had while it was a constituent part of the rock.
It may further be noted that the chief of these soil-forming
agencies act more vigorously in arid than in humid sections. Under
the cloudless sky and dry atmosphere of regions of limited rainfall,
the daily and seasonal temperature changes are much greater than in
sections of greater rainfall. Consequently the pulverization of
rocks goes on most rapidly in dry-farm districts. Constant heavy
winds, which as soil formers are second only to temperature changes
and freezing water, are also usually more common in arid than in
humid countries. This is strikingly shown, for instance, on the
Colorado desert and the Great Plains.
The rock powder formed by the processes above described is
continually being acted upon by agencies, the effect of which is to
change its chemical composition. Chief of these agencies is _water,
_which exerts a solvent action on all known substances. Pure water
exerts a strong solvent action, but when it has been rendered impure
by a variety of substances, naturally occurring, its solvent action
is greatly increased.
The most effective water impurity, considering soil formation, is
the gas, _carbon dioxid. _This gas is formed whenever plant or
animal substances decay, and is therefore found, normally, in the
atmosphere and in soils. Rains or flowing water gather the carbon
dioxid from the atmosphere and the soil; few natural waters are free
from it. The hardest rock particles are disintegrated by carbonated
water, while limestones, or rocks containing lime, are readily
dissolved.
The result of the action of carbonated water upon soil particles is
to render soluble, and therefore more available to plants, many of
the important plant-foods. In this way the action of water, holding
in solution carbon dioxid and other substances, tends to make the
soil more fertile.
The second great chemical agency of soil formation is the oxygen of
the air. Oxidation is a process of more or less rapid burning, which
tends to accelerate the disintegration of rocks.
Finally, the _plants _growing in soils are powerful agents of soil
formation. First, the roots forcing their way into the soil exert a
strong pressure which helps to pulverize the soil grains; secondly,
the acids of the plant roots actually dissolve the soil, and third,
in the mass of decaying plants, substances are formed, among them
carbon dioxid, that have the power of making soils more soluble.
It may be noted that moisture, carbon dioxid, and vegetation, the
three chief agents inducing chemical changes in soils, are most
active in humid districts. While, therefore, the physical agencies
of soil formation are most active in arid climates, the same cannot
be said of the chemical agencies. However, whether in arid or humid
climates, the processes of soil formation, above outlined, are
essentially those of the "fallow" or resting-period given to
dry-farm lands. The fallow lasts for a few months or a year, while
the process of soil formation is always going on and has gone on for
ages; the result, in quality though not in quantity, is the
same--the rock particles are pulverized and the plant-foods are
liberated. It must be remembered in this connection that climatic
differences may and usually do influence materially the character of
soils formed from one and the same kind of rock.
Characteristics of arid soils
The net result of the processes above described Is a rock powder
containing a great variety of sizes of soil grains intermingled with
clay. The larger soil grains are called sand; the smaller, silt, and
those that are so small that they do not settle from quiet water
after 24 hours are known as clay.
Clay differs materially from sand and silt, not only in size of
particles, but also in properties and formation. It is said that
clay particles reach a degree of fineness equal to 1/2500 of an
inch. Clay itself, when wet and kneaded, becomes plastic and
adhesive and is thus easily distinguished from sand. Because of
these properties, clay is of great value in holding together the
larger soil grains in relatively large aggregates which give soils
the desired degree of filth. Moreover, clay is very retentive of
water, gases, and soluble plant-foods, which are important factors
in successful agriculture. Soils, in fact, are classified according
to the amount of clay that they contain. Hilgard suggests the
following classification:--
Very sandy soils 0.5 to 3 per cent clay
Ordinary sandy soils 3.0 to 10 per cent clay
Sandy loams 10.0 to 15 per cent clay
Clay loams 15.0 to 25 per cent clay
Clay soils 25.0 to 35 per cent clay
Heavy clay soils 35.0 per cent and over
Clay may be formed from any rock containing some form of _combined
silica _(quartz). Thus, granites and crystalline rocks generally,
volcanic rocks, and shales will produce clay if subjected to the
proper climatic conditions. In the formation of clay, the extremely
fine soil particles are attacked by the soil water and subjected to
deep-going chemical changes. In fact, clay represents the most
finely pulverized and most highly decomposed and hence in a measure
the most valuable portion of the soil. In the formation of clay,
water is the most active agent, and under humid conditions its
formation is most rapid.
It follows that dry-farm soils formed under a more or less rainless
climate contain less clay than do humid soils. This difference is
characteristic, and accounts for the statement frequently made that
heavy clay soils are not the best for dry-farm purposes. The fact
is, that heavy clay soils are very rare in arid regions; if found at
all, they have probably been formed under abnormal conditions, as in
high mountain valleys, or under prehistoric humid climates.
_Sand.--_The sand-forming rocks that are not capable of clay
production usually consist of _uncombined silica _or quartz, which
when pulverized by the soil-forming agencies give a comparatively
barren soil. Thus it has come about that ordinarily a clayey soil is
considered "strong" and a sandy soil "weak." Though this distinction
is true in humid climates where clay formation is rapid, it is not
true in arid climates, where true clay is formed very slowly. Under
conditions of deficient rainfall, soils are naturally less clayey,
but as the sand and silt particles are produced from rocks which
under humid conditions would yield clay, arid soils are not
necessarily less fertile.
Experiment has shown that the fertility in the sandy soils of arid
sections is as large and as available to plants as in the clayey
soils of humid regions. Experience in the arid section of America,
in Egypt, India, and other desert-like regions has further proved
that the sands of the deserts produce excellent crops whenever water
is applied to them. The prospective dry-farmer, therefore, need not
be afraid of a somewhat sandy soil, provided it has been formed
under arid conditions. In truth, a degree of sandiness is
characteristic of dry-farm soils.
The _humus _content forms another characteristic difference between
arid and humid soils. In humid regions plants cover the soil
thickly; in arid regions they are bunched scantily over the surface;
in the former case the decayed remnants of generations of plants
form a large percentage of humus in the upper soil; in the latter,
the scarcity of plant life makes the humus content low. Further,
under an abundant rainfall the organic matter in the soil rots
slowly; whereas in dry warm climates the decay is very complete. The
prevailing forces in all countries of deficient rainfall therefore
tend to yield soils low in humus.
While the total amount of humus in arid soils is very much lower
than in humid soils, repeated investigation has shown that it
contains about 3-1/2 times more nitrogen than is found in humus
formed under an abundant rainfall. Owing to the prevailing sandiness
of dry-farm soils, humus is not needed so much to give the proper
filth to the soil as in the humid countries where the content of
clay is so much higher. Since, for dry-farm purposes, the nitrogen
content is the most important quality of the humus, the difference
between arid and humid soils, based upon the humus content, is not
so great as would appear at first sight.
_Soil and subsoil.--_In countries of abundant rainfall, a great
distinction exists between the soil and the subsoil. The soil is
represented by the upper few inches which are filled with the
remnants of decayed vegetable matter and modified by plowing,
harrowing, and other cultural operations. The subsoil has been
profoundly modified by the action of the heavy rainfall, which, in
soaking through the soil, has carried with it the finest soil
grains, especially the clay, into the lower soil layers.
In time, the subsoil has become more distinctly clayey than the
topsoil. Lime and other soil ingredients have likewise been carried
down by the rains and deposited at different depths in the soil or
wholly washed away. Ultimately, this results in the removal from the
topsoil of the necessary plant-foods and the accumulation in the
subsoil of the fine clay particles which so compact the subsoil as
to make it difficult for roots and even air to penetrate it. The
normal process of weathering or soil disintegration will then go on
most actively in the topsoil and the subsoil will remain unweathered
and raw. This accounts for the well-known fact that in humid
countries any subsoil that may have been plowed up is reduced to a
normal state of fertility and crop production only after several
years of exposure to the elements. The humid farmer, knowing this,
is usually very careful not to let his plow enter the subsoil to any
great depth.
In the arid regions or wherever a deficient rainfall prevails, these
conditions are entirely reversed. The light rainfall seldom
completely fills the soil pores to any considerable depth, but it
rather moves down slowly as a him, enveloping the soil grains. The
soluble materials of the soil are, in part at least, dissolved and
carried down to the lower limit of the rain penetration, but the
clay and other fine soil particles are not moved downward to any
great extent. These conditions leave the soil and subsoil of
approximately equal porosity. Plant roots can then penetrate the
soil deeply, and the air can move up and down through the soil mass
freely and to considerable depths. As a result, arid soils are
weathered and made suitable for plant nutrition to very great
depths. In fact, in dry-farm regions there need be little talk about
soil and subsoil, since the soil is uniform in texture and usually
nearly so in composition, from the top down to a distance of many
feet.
Many soil sections 50 or more feet in depth are exposed in the
dry-farming territory of the United States, and it has often been
demonstrated that the subsoil to any depth is capable of producing,
without further weathering, excellent yields of crops. This
granular, permeable structure, characteristic of arid soils, is
perhaps the most important single quality resulting from rock
disintegration under arid conditions. As Hilgard remarks, it would
seem that the farmer in the arid region owns from three to four
farms, one above the other, as compared with the same acreage in the
eastern states.
This condition is of the greatest importance in developing the
principles upon which successful dry-farming rests. Further, it may
be said that while in the humid East the farmer must be extremely
careful not to turn up with his plow too much of the inert subsoil,
no such fear need possess the western farmer. On the contrary, he
should use his utmost endeavor to plow as deeply as possible in
order to prepare the very best reservoir for the falling waters and
a place for the development of plant roots.
_Gravel seams.--_It need be said, however, that in a number of
localities in the dry-farm territory the soils have been deposited
by the action of running water in such a way that the otherwise
uniform structure of the soil is broken by occasional layers of
loose gravel. While this is not a very serious obstacle to the
downward penetration of roots, it is very serious in dry-farming,
since any break in the continuity of the soil mass prevents the
upward movement of water stored in the lower soil depths. The
dry-farmer should investigate the soil which he intends to use to a
depth of at least 8 to 10 feet to make sure, first of all, that he
has a continuous soil mass, not too clayey in the lower depths, nor
broken by deposits of gravel.
_Hardpan.--_Instead of the heavy clay subsoil of humid regions, the
so-called hardpan occurs in regions of limited rainfall. The annual
rainfall, which is approximately constant, penetrates from year to
year very nearly to the same depth. Some of the lime found so
abundantly in arid soils is dissolved and worked down yearly to the
lower limit of the rainfall and left there to enter into combination
with other soil ingredients. Continued through long periods of time
this results in the formation of a layer of calcareous material at
the average depth to which the rainfall has penetrated the soil. Not
only is the lime thus carried down, but the finer particles are
carried down in like manner. Especially where the soil is poor in
lime is the clay worked down to form a somewhat clayey hardpan. A
hardpan formed in such a manner is frequently a serious obstacle to
the downward movement of the roots, and also prevents the annual
precipitation from moving down far enough to be beyond the influence
of the sunshine and winds. It is fortunate, however, that in the
great majority of instances this hardpan gradually disappears under
the influence of proper methods of dry-farm tillage. Deep plowing
and proper tillage, which allow the rain waters to penetrate the
soil, gradually break up and destroy the hardpan, even when it is 10
feet below the surface. Nevertheless, the farmer should make sure
whether or not the hardpan does exist in the soil and plan his
methods accordingly. If a hardpan is present, the land must be
fallowed more carefully every other year, so that a large quantity
of water may be stored in the soil to open and destroy the hardpan.
Of course, in arid as in humid countries, it often happens that a
soil is underlaid, more or less near the surface, by layers of rock,
marl deposits, and similar impervious or hurtful substances. Such
deposits are not to be classed with the hardpans that occur normally
wherever the rainfall is small.
_Leaching.--_Fully as important as any of the differences above
outlined are those which depend definitely upon the leaching power
of a heavy rainfall. In countries where the rainfall is 30 inches or
over, and in many places where the rainfall is considerably less,
the water drains through the soil into the standing ground water.
There is, therefore, in humid countries, a continuous drainage
through the soil after every rain, and in general there is a steady
downward movement of soil-water throughout the year. As is clearly
shown by the appearance, taste, and chemical composition of drainage
waters, this process leaches out considerable quantities of the
soluble constituents of the soil.
When the soil contains decomposing organic matter, such as roots,
leaves, stalks, the gas carbon dioxid is formed, which, when
dissolved in water, forms a solution of great solvent power. Water
passing through well-cultivated soils containing much humus leaches
out very much more material than pure water could do. A study of the
composition of the drainage waters from soils and the waters of the
great rivers shows that immense quantities of soluble soil
constituents are taken out of the soil in countries of abundant
rainfall. These materials ultimately reach the ocean, where they are
and have been concentrated throughout the ages. In short, the
saltiness of the ocean is due to the substances that have been
washed from the soils in countries of abundant rainfall.
In arid regions, on the other hand, the rainfall penetrates the soil
only a few feet. In time, it is returned to the surface by the
action of plants or sunshine and evaporated into the air. It is true
that under proper methods of tillage even the light rainfall of arid
and semiarid regions may he made to pass to considerable soil
depths, yet there is little if any drainage of water through the
soil into the standing ground water. The arid regions of the world,
therefore, contribute proportionately a small amount of the
substances which make up the salt of the sea.
_Alkali soils.--_Under favorable conditions it sometimes happens
that the soluble materials, which would normally be washed out of
humid soils, accumulate to so large a degree in arid soils as to
make the lands unfitted for agricultural purposes. Such lands are
called alkali lands. Unwise irrigation in arid climates frequently
produces alkali spots, but many occur naturally. Such soils should
not be chosen for dry-farm purposes, for they are likely to give
trouble.
_Plant-food content.--_This condition necessarily leads at once to
the suggestion that the soils from the two regions must differ
greatly in their fertility or power to produce and sustain plant
life. It cannot be believed that the water-washed soils of the East
retain as much fertility as the dry soils of the West. Hilgard has
made a long and elaborate study of this somewhat difficult question
and has constructed a table showing the composition of typical soils
of representative states in the arid and humid regions. The
following table shows a few of the average results obtained by
him:--
Partial Percentage Composition
Source of soil Humid Arid
Number of samples analyzed 696 573
Insoluble residue 84.17 69.16
Soluble silica 4.04 6.71
Alumina 3.66 7.61
Lime 0.13 1.43
Potash 0.21 0.67
Phos. Acid 0.12 0.16
Humus 1.22 1.13
Soil chemists have generally attempted to arrive at a determination
of the fertility of soil by treating a carefully selected and
prepared sample with a certain amount of acid of definite strength.
The portion which dissolves under the influence of acids has been
looked upon as a rough measure of the possible fertility of the
soil.
The column headed "Insoluble Residue" shows the average proportions
of arid and humid soils which remain undissolved by acids. It is
evident at once that the humid soils are much less soluble in acids
than arid soils, the difference being 84 to 69. Since the only
plant-food in soils that may be used for plant production is that
which is soluble, it follows that it is safe to assume that arid
soils are generally more fertile than humid soils. This is borne out
by a study of the constituents of the soil. For instance, potash,
one of the essential plant foods ordinarily present in sufficient
amount, is found in humid soils to the extent of 0.21 per cent,
while in arid soils the quantity present is 0.67 per cent, or over
three times as much. Phosphoric acid, another of the very important
plant-foods, is present in arid soils in only slightly higher
quantities than in humid soils. This explains the somewhat
well-known fact that the first fertilizer ordinarily required by
arid soils is some form of phosphorus:
The difference in the chemical composition of arid and humid soils
is perhaps shown nowhere better than in the lime content. There is
nearly eleven times more lime in arid than in humid soils.
Conditions of aridity favor strongly the formation of lime, and
since there is very little leaching of the soil by rainfall, the
lime accumulates in the soil.
The presence of large quantities of lime in arid soils has a number
of distinct advantages, among which the following are most
important: (1) It prevents the sour condition frequently present in
humid climates, where much organic material is incorporated with the
soil. (2) When other conditions are favorable, it encourages
bacterial life which, as is now a well-known fact, is an important
factor in developing and maintaining soil fertility. (3) By somewhat
subtle chemical changes it makes the relatively small percentages of
other plant-foods notably phosphoric acid and potash, more available
for plant growth. (4) It aids to convert rapidly organic matter into
humus which represents the main portion of the nitrogen content of
the soil.
Of course, an excess of lime in the soil may be hurtful, though less
so in arid than in humid regions. Some authors state that from 8 to
20 per cent of calcium carbonate makes a soil unfitted for plant
growth. There are, however, a great many agricultural soils covering
large areas and yielding very abundant crops which contain very much
larger quantities of calcium carbonate. For instance, in the Sanpete
Valley of Utah, one of the most fertile sections of the Great Basin,
agricultural soils often contain as high as 40 per cent of calcium
carbonate, without injury to their crop-producing power.
In the table are two columns headed "Soluble Silica" and "Alumina,"
in both of which it is evident that a very much larger per cent is
found in the arid than in the humid soils. These soil constituents
indicate the condition of the soil with reference to the
availability of its fertility for plant use. The higher the
percentage of soluble silica and alumina, the more thoroughly
decomposed, in all probability, is the soil as a whole and the more
readily can plants secure their nutriment from the soil. It will be
observed from the table, as previously stated, that more humus is
found in humid than in arid soils, though the difference is not so
large as might be expected. It should be recalled, however, that the
nitrogen content of humus formed under rainless conditions is many
times larger than that of humus formed in rainy countries, and that
the smaller per cent of humus in dry-farming countries is thereby
offset.
All in all, the composition of arid soils is very much more
favorable to plant growth than that of humid soils. As will be shown
in Chapter IX, the greater fertility of arid soils is one of the
chief reasons for dry-farming success. Depth of the soil alone does
not suffice. There must be a large amount of high fertility
available for plants in order that the small amount of water can be
fully utilized in plant growth.
_Summary of characteristics.--_Arid soils differ from humid soils in
that they contain: less clay; more sand, but of fertile nature
because it is derived from rocks that in humid countries would
produce clay; less humus, but that of a kind which contains about
3-1/2 times more nitrogen than the humus of humid soils; more lime,
which helps in a variety of ways to improve the agricultural value
of soils; more of all the essential plant-foods, because the
leaching by downward drainage is very small in countries of limited
rainfall.
Further, arid soils show no real difference between soil and
subsoil; they are deeper and more permeable; they are more uniform
in structure; they have hardpans instead of clay subsoil, which,
however, disappear under the influence of cultivation; their
subsoils to a depth of ten feet or more are as fertile as the
topsoil, and the availability of the fertility is greater. The
failure to recognize these characteristic differences between arid
and humid soils has been the chief cause for many crop failures in
the more or less rainless regions of the world.
This brief review shows that, everything considered, arid soils are
superior to humid soils. In ease of handling, productivity,
certainty of crop-lasting quality, they far surpass the soils of the
countries in which scientific agriculture was founded. As Hilgard
has suggested, the historical datum that the majority of the most
populous and powerful historical peoples of the world have been
located on soils that thirst for water, may find its explanation in
the intrinsic value of arid soils. From Babylon to the United States
is a far cry; but it is one that shouts to the world the superlative
merits of the soil that begs for water. To learn how to use the
"desert" is to make it "blossom like the rose."
Soil divisions
The dry-farm territory of the United States may be divided roughly
into five great soil districts, each of which includes a great
variety of soil types, most of which are poorly known and mapped.
These districts are:--
1. Great Plains district.
2. Columbia River district
3. Great Basin district.
4. Colorado River district.
5. California district.
_Great Plains district.--_On the eastern slope of the Rocky
Mountains, extending eastward to the extreme boundary of the
dry-farm territory, are the soils of the High Plains and the Great
Plains. This vast soil district belongs to the drainage basin of the
Missouri, and includes North and South Dakota, Nebraska, Kansas,
Oklahoma, and parts of Montana, Wyoming, Colorado, New Mexico,
Texas, and Minnesota. The soils of this district are usually of high
fertility. They have good lasting power, though the effect of the
higher rainfall is evident in their composition. Many of the
distinct types of the plains soils have been determined with
considerable care by Snyder and Lyon, and may be found described in
Bailey's "Cyclopedia of American Agriculture," Vol. I.
_Columbia River district.--_The second great soil district of the
dry-farming territory is located in the drainage basin of the
Columbia River, and includes Idaho and the eastern two thirds of
Washington and Oregon. The high plains of this soil district are
often spoken of as the Palouse country. The soils of the western
part of this district are of basaltic origin; over the southern part
of Idaho the soils have been made from a somewhat recent lava flow
which in many places is only a few feet below the surface. The soils
of this district are generally of volcanic origin and very much
alike. They are characterized by the properties which normally
belong to volcanic soils; somewhat poor in lime, but rich in potash
and phosphoric acid. They last well under ordinary methods of
tillage.
_The Great Basin.--_The third great soil district is included in the
Great Basin, which covers nearly all of Nevada, half of Utah, and
takes small portions out of Idaho, Oregon, and southern California.
This basin has no outlet to the sea. Its rivers empty into great
saline inland lakes, the chief of which is the Great Salt Lake. The
sizes of these interior lakes are determined by the amounts of water
flowing into them and the rates of evaporation of the water into the
dry air of the region.
In recent geological times, the Great Basin was filled with water,
forming a vast fresh-water lake known as Lake Bonneville, which
drained into the Columbia River. During the existence of this lake,
soil materials were washed from the mountains into the lake and
deposited on the lake bottom. When at length, the lake disappeared,
the lake bottom was exposed and is now the farming lands of the
Great Basin district. The soils of this district are characterized
by great depth and uniformity, an abundance of lime, and all the
essential plant-foods with the exception of phosphoric acid, which,
while present in normal quantities, is not unusually abundant. The
Great Basin soils are among the most fertile on the American
Continent.
_Colorado River district.--_The fourth soil district lies in the
drainage basin of the Colorado River It includes much of the
southern part of Utah, the eastern part of Colorado, part of New
Mexico, nearly all of Arizona, and part of southern California. This
district, in its northern part, is often spoken of as the High
Plateaus. The soils are formed from the easily disintegrated rocks
of comparatively recent geological origin, which themselves are said
to have been formed from deposits in a shallow interior sea which
covered a large part of the West. The rivers running through this
district have cut immense canons with perpendicular walls which make
much of this country difficult to traverse. Some of the soils are of
an extremely fine nature, settling firmly and requiring considerable
tillage before they are brought to a proper condition of tilth. In
many places the soils are heavily charged with calcium sulfate, or
crystals of the ordinary land plaster. The fertility of the soils,
however, is high, and when they are properly cultivated, they yield
large and excellent crops.
_California district.--_The fifth soil district lies in California
in the basin of the Sacramento and San Joaquin rivers. The soils are
of the typical arid kind of high fertility and great lasting powers.
They represent some of the most valuable dry-farm districts of the
West. These soils have been studied in detail by Hilgard.
_Dry-farming in the five districts.--_It is interesting to note that
in all of these five great soil districts dry-farming has been tried
with great success. Even in the Great Basin and the Colorado River
districts, where extreme desert conditions often prevail and where
the rainfall is slight, it has been found possible to produce
profitable crops without irrigation. It is unfortunate that the
study of the dry-farming territory of the United States has not
progressed far enough to permit a comprehensive and correct mapping
of its soils. Our knowledge of this subject is, at the best,
fragmentary. We know, however, with certainty that the properties
which characterize arid soils, as described in this chapter' are
possessed by the soils of the dry-farming territory, including the
five great districts just enumerated. The characteristics of arid id
soils increase as the rainfall decreases and other conditions of
aridity increase. They are less marked as we go eastward or westward
toward the regions of more abundant rainfall; that is to say, the
most highly developed arid soils are found in the Great Basin and
Colorado River districts. The least developed are on the eastern
edge of the Great Plains.
The judging of soils
A chemical analysis of a soil, unless accompanied by a large amount
of other information, is of little value to the farmer. The main
points in judging a prospective dry-farm are: the depth of the soil,
the uniformity of the soil to a depth of at least 10 feet, the
native vegetation, the climatic conditions as relating to early and
late frosts, the total annual rainfall and its distribution, and the
kinds and yields of crops that have been grown in the neighborhood.
The depth of the soil is best determined by the use of an auger. A
simple soil auger is made from the ordinary carpenter's auger, 1-1/2
to 2 inches in diameter, by lengthening its shaft to 3 feet or more.
Where it is not desirable to carry sectional augers, it is often
advisable to have three augers made: one 3 feet, the other 6, and
the third 9 or 10 feet in length. The short auger is used first and
the others afterwards as the depth of the boring increases. The
boring should he made in a large number of average
places--preferably one boring or more on each acre if time and
circumstances permit--and the results entered on a map of the farm.
The uniformity of the soil is observed as the boring progresses. If
gravel layers exist, they will necessarily stop the progress of the
boring. Hardpans of any kind will also be revealed by such an
examination.
The climatic information must be gathered from the local weather
bureau and from older residents of the section.
The native vegetation is always an excellent index of dry-farm
possibilities. If a good stand of native grasses exists, there can
scarcely be any doubt about the ultimate success of dry-farming
under proper cultural methods. A healthy crop of sagebrush is an
almost absolutely certain indication that farming without irrigation
is feasible. The rabbit brush of the drier regions is also usually a
good indication, though it frequently indicates a soil not easily
handled. Greasewood, shadscale, and other related plants ordinarily
indicate heavy clay soils frequently charged with alkali. Such soils
should be the last choice for dry-farming purposes, though they
usually give good satisfaction under systems of irrigation. If the
native cedar or other native trees grow in profusion, it is another
indication of good dry-farm possibilities.
CHAPTER VI
THE ROOT SYSTEMS OF PLANTS
The great depth and high fertility of the soils of arid and semiarid
regions have made possible the profitable production of agricultural
plants under a rainfall very much lower than that of humid regions.
To make the principles of this system fully understood, it is
necessary to review briefly our knowledge of the root systems of
plants growing under arid conditions.
Functions of roots
The roots serve at least three distinct uses or purposes: First,
they give the plant a foothold in the earth; secondly, they enable
the plant to secure from the soil the large amount of water needed
in plant growth, and, thirdly, they enable the plant to secure the
indispensable mineral foods which can be obtained only from the
soil. So important is the proper supply of water and food in the
growth of a plant that, in a given soil, the crop yield is usually
in direct proportion to the development of the root system. Whenever
the roots are hindered in their development, the growth of the plant
above ground is likewise retarded, and crop failure may result. The
importance of roots is not fully appreciated because they are hidden
from direct view. Successful dry-farming consists, largely in the
adoption of practices that facilitate a full and free development-of
plant roots. Were it not that the nature of arid soils, as explained
in preceding chapters, is such that full root development is
comparatively easy, it would probably be useless to attempt to
establish a system of dry-farming.
Kinds of roots
The root is the part of the plant that is found underground. It has
numerous branches, twigs, and filaments. The root which first forms
when the seed bursts is known as the primary root. From this primary
root other roots develop, which are known as secondary roots. When
the primary root grows more rapidly than the secondary roots, the
so-called taproot, characteristic of lucerne, clover, and similar
plants, is formed. When, on the other hand, the taproot grows slowly
or ceases its growth, and the numerous secondary roots grow long, a
fibrous root system results, which is characteristic of the cereals,
grasses, corn, and other similar plants. With any type of root, the
tendency of growth is downward; though under conditions that are not
favorable for the downward penetration of the roots the lateral
extensions may be very large and near the surface
Extent of roots
A number of investigators have attempted to determine the weight of
the roots as compared with the weight of the plant above ground, hut
the subject, because of its great experimental difficulties, has not
been very accurately explained. Schumacher, experimenting about
1867, found that the roots of a well-established field of clover
weighed as much as the total weight of the stems and leaves of the
year's crop, and that the weight of roots of an oat crop was 43 per
cent of the total weight of seed and straw. Nobbe, a few years
later, found in one of his experiments that the roots of timothy
weighed 31 per cent of the weight of the hay. Hosaeus, investigating
the same subject about the same time, found that the weight of roots
of one of the brome grasses was as great as the weight of the part
above ground; of serradella, 77 per cent; of flax, 34 per cent; of
oats, 14 per cent; of barley, 13 per cent, and of peas, 9 per cent.
Sanborn, working at the Utah Station in 1893, found results very
much the same
Although these results are not concordant, they show that the weight
of the roots is considerable, in many cases far beyond the belief of
those who have given the subject little or no attention. It may be
noted that on the basis of the figures above obtained, it is very
probable that the roots in one acre of an average wheat crop would
weigh in the neighborhood of a thousand pounds--possibly
considerably more. It should be remembered that the investigations
which yielded the preceding results were all conducted in humid
climates and at a time when the methods for the study of the root
systems were poorly developed. The data obtained, therefore,
represent, in all probability, minimum results which would be
materially increased should the work be repeated now.
The relative weights of the roots and the stems and the leaves do
not alone show the large quantity of roots; the total lengths of the
roots are even more striking. The German investigator, Nobbe, in a
laborious experiment conducted about 1867, added the lengths of all
the fine roots from each of various plants. He found that the total
length of roots, that is, the sum of the lengths of all the roots,
of one wheat plant was about 268 feet, and that the total length of
the roots of one plant of rye was about 385 feet. King, of
Wisconsin, estimates that in one of his experiments, one corn plant
produced in the upper 3 feet of soil 1452 feet of roots. These
surprisingly large numbers indicate with emphasis the thoroughness
with which the roots invade the soil.
Depth of root penetration
The earlier root studies did not pretend to determine the depth to
which roots actually penetrate the earth. In recent years, however,
a number of carefully conducted experiments were made by the New
York, Wisconsin, Minnesota, Kansas, Colorado, and especially the
North Dakota stations to obtain accurate information concerning the
depth to which agricultural plants penetrate soils. It is somewhat
regrettable, for the purpose of dry-farming, that these states, with
the exception of Colorado, are all in the humid or sub-humid area of
the United States. Nevertheless, the conclusions drawn from the work
are such that they may be safely applied in the development of the
principles of dry-farming.
There is a general belief among farmers that the roots of all
cultivated crops are very near the surface and that few reach a
greater depth than one or two feet. The first striking result of the
American investigations was that every crop, without exception,
penetrates the soil deeper than was thought possible in earlier
days. For example, it was found that corn roots penetrated fully
four feet into the ground and that they fully occupied all of the
soil to that depth.
On deeper and somewhat drier soils, corn roots went down as far as
eight feet. The roots of the small grains,--wheat, oats,
barley,--penetrated the soil from four to eight or ten feet. Various
perennial grasses rooted to a depth of four feet the first year; the
next year, five and one half feet; no determinations were made of
the depth of the roots in later years, though it had undoubtedly
increased. Alfalfa was the deepest rooted of all the crops studied
by the American stations. Potato roots filled the soil fully to a
depth of three feet; sugar beets to a depth of nearly four feet.
Sugar Beet Roots
In every case, under conditions prevailing in the experiments, and
which did not have in mind the forcing of the roots down to
extraordinary depths, it seemed that the normal depth of the roots
of ordinary field crops was from three to eight feet. Sub-soiling
and deep plowing enable the roots to go deeper into the soil. This
work has been confirmed in ordinary experience until there can be
little question about the accuracy of the results.
Almost all of these results were obtained in humid climates on humid
soils, somewhat shallow, and underlain by a more or less infertile
subsoil. In fact, they were obtained under conditions really
unfavorable to plant growth. It has been explained in Chapter V that
soils formed under arid or semiarid conditions are uniformly deep
and porous and that the fertility of the subsoil is, in most cases,
practically as great as of the topsoil. There is, therefore, in arid
soils, an excellent opportunity for a comparatively easy penetration
of the roots to great depths and, because of the available
fertility, a chance throughout the whole of the subsoil for ample
root development. Moreover, the porous condition of the soil permits
the entrance of air, which helps to purify the soil atmosphere and
thereby to make the conditions more favorable for root development.
Consequently it is to be expected that, in arid regions, roots will
ordinarily go to a much greater depth than in humid regions.
It is further to be remembered that roots are in constant search of
food and water and are likely to develop in the directions where
there is the greatest abundance of these materials. Under systems of
dry-farming the soil water is stored more or less uniformly to
considerable depths--ten feet or more--and in most cases the
percentage of moisture in the spring and summer is as large or
larger some feet below the surface than in the upper two feet. The
tendency of the root is, then, to move downward to depths where
there is a larger supply of water. Especially is this tendency
increased by the available soil fertility found throughout the whole
depth of the soil mass.
It has been argued that in many of the irrigated sections the roots
do not penetrate the soil to great depths. This is true, because by
the present wasteful methods of irrigation the plant receives so
much water at such untimely seasons that the roots acquire the habit
of feeding very near the surface where the water is so lavishly
applied. This means not only that the plant suffers more greatly in
times of drouth, but that, since the feeding ground of the roots is
smaller, the crop is likely to be small.
These deductions as to the depth to which plant roots will penetrate
the soil in arid regions are fully corroborated by experiments and
general observation. The workers of the Utah Station have repeatedly
observed plant roots on dry-farms to a depth of ten feet. Lucerne
roots from thirty to fifty feet in length are frequently exposed in
the gullies formed by the mountain torrents. Roots of trees,
similarly, go down to great depths. Hilgard observes that he has
found roots of grapevines at a depth of twenty-two feet below the
surface, and quotes Aughey as having found roots of the native
Shepherdia in Nebraska to a depth of fifty feet. Hilgard further
declares that in California fibrous-rooted plants, such as wheat and
barley, may descend in sandy soils from four to seven feet. Orchard
trees in the arid West, grown properly, are similarly observed to
send their roots down to great depths. In fact, it has become a
custom in many arid regions where the soils are easily penetrable to
say that the root system of a tree corresponds in extent and
branching to the part of the tree above ground.
Now, it is to be observed that, generally, plants grown in dry
climates send their roots straight down into the soil; whereas in
humid climates, where the topsoil is quite moist and the subsoil is
hard, roots branch out laterally and fill the upper foot or two of
the soil. A great deal has been said and written about the danger of
deep cultivation, because it tends to injure the roots that feed
near the surface. However true this may be in humid countries, it is
not vital in the districts primarily interested in dry-farming; and
it is doubtful if the objection is as valid in humid countries as is
often declared. True, deep cultivation, especially when performed
near the plant or tree, destroys the surface-feeding roots, but this
only tends to compel the deeper lying roots to make better use of
the subsoil.
When, as in arid regions, the subsoil is fertile and furnishes a
sufficient amount of water, destroying the surface roots is no
handicap whatever. On the contrary, in times of drouth, the
deep-lying roots feed and drink at their leisure far from the hot
sun or withering winds, and the plants survive and arrive at rich
maturity, while the plants with shallow roots wither and die or are
so seriously injured as to produce an inferior crop. Therefore, in
the system of dry-farming as developed in this volume, it must be
understood that so far as the farmer has power, the roots must be
driven downward into the soil, and that no injury needs to be
apprehended from deep and vigorous cultivation.
One of the chief attempts of the dry-farmer must be to see to it
that the plants root deeply. This can be done only by preparing the
right kind of seed-bed and by having the soil in its lower depths
well-stored with moisture, so that the plants may be invited to
descend. For that reason, an excess of moisture in the upper soil
when the young plants are rooting is really an injury to them.
CHAPTER VII
STORING WATER IN THE SOIL
The large amount of water required for the production of plant
substance is taken from the soil by the roots. Leaves and stems do
not absorb appreciable quantities of water. The scanty rainfall of
dry-farm districts or the more abundant precipitation of humid
regions must, therefore, be made to enter the soil in such a manner
as to be readily available as soil-moisture to the roots at the
right periods of plant growth.
In humid countries, the rain that falls during the growing season is
looked upon, and very properly, as the really effective factor in
the production of large crops. The root systems of plants grown
under such humid conditions are near the surface, ready to absorb
immediately the rains that fall, even if they do not soak deeply
into the soil. As has been shown in Chapter IV, it is only over a
small portion of the dry-farm territory that the bulk of the scanty
precipitation occurs during the growing season. Over a large portion
of the arid and semiarid region the summers are almost rainless and
the bulk of the precipitation comes in the winter, late fall, or
early spring when plants are not growing. If the rains that fall
during the growing season are indispensable in crop production, the
possible area to be reclaimed by dry-farming will be greatly
limited. Even when much of the total precipitation comes in summer,
the amount in dry-farm districts is seldom sufficient for the proper
maturing of crops. In fact, successful dry-farming depends chiefly
upon the success with which the rains that fall during any season of
the year may be stored and kept in the soil until needed by plants
in their growth. The fundamental operations of dry-farming include a
soil treatment which enables the largest possible proportion of the
annual precipitation to be stored in the soil. For this purpose, the
deep, somewhat porous soils, characteristic of arid regions, are
unusually well adapted.
Alway's demonstration
An important and unique demonstration of the possibility of bringing
crops to maturity on the moisture stored in the soil at the time of
planting has been made by Alway. Cylinders of galvanized iron, 6
feet long, were filled with soil as nearly as possible in its
natural position and condition Water was added until seepage began,
after which the excess was allowed to drain away. When the seepage
had closed, the cylinders were entirely closed except at the
surface. Sprouted grains of spring wheat were placed in the moist
surface soil, and 1 inch of dry soil added to the surface to prevent
evaporation. No more water was added; the air of the greenhouse was
kept as dry as possible. The wheat developed normally. The first ear
was ripe in 132 days after planting and the last in 143 days. The
three cylinders of soil from semiarid western Nebraska produced 37.8
grams of straw and 29 ears, containing 415 kernels weighing 11.188
grams. The three cylinders of soil from humid eastern Nebraska
produced only 11.2 grams of straw and 13 ears containing 114
kernels, weighing 3 grams. This experiment shows conclusively that
rains are not needed during the growing season, if the soil is well
filled with moisture at seedtime, to bring crops to maturity.
What becomes of the rainfall?
The water that falls on the land is disposed of in three ways:
First, under ordinary conditions, a large portion runs off without
entering the soil; secondly, a portion enters the soil, but remains
near the surface, and is rapidly evaporated back into the air; and,
thirdly, a portion enters the lower soil layers, from which it is
removed at later periods by several distinct processes. The run-off
is usually large and is a serious loss, especially in dry-farming
regions, where the absence of luxuriant vegetation, the somewhat
hard, sun-baked soils, and the numerous drainage channels, formed by
successive torrents, combine to furnish the rains with an easy
escape into the torrential rivers. Persons familiar with arid
conditions know how quickly the narrow box canyons, which often
drain thousands of square miles, are filled with roaring water after
a comparatively light rainfall.
The run-off
The proper cultivation of the soil diminishes very greatly the loss
due to run-off, but even on such soils the proportion may often be
very great. Farrel observed at one of the Utah stations that during
a torrential rain--2.6 inches in 4 hours--the surface of the summer
fallowed plats was packed so solid that only one fourth inch, or
less than one tenth of the whole amount, soaked into the soil, while
on a neighboring stubble field, which offered greater hindrance to
the run-off, 1-1/2 inches or about 60 per cent were absorbed.
It is not possible under any condition to prevent the run-off
altogether, although it can usually be reduced exceedingly. It is a
common dry-farm custom to plow along the slopes of the farm instead
of plowing up and down them. When this is done, the water which runs
down the slopes is caught by the succession of furrows and in that
way the runoff is diminished. During the fallow season the disk and
smoothing harrows are run along the hillsides for the same purpose
and with results that are nearly always advantageous to the
dry-farmer. Of necessity, each man must study his own farm in order
to devise methods that will prevent the run-off.
The structure of soils
Before examining more closely the possibility of storing water in
soils a brief review of the structure of soils is desirable. As
previously explained, soil is essentially a mixture of disintegrated
rock and the decomposing remains of plants. The rock particles which
constitute the major portion of soils vary greatly in size. The
largest ones are often 500 times the sizes of the smallest. It would
take 50 of the coarsest sand particles, and 25,000 of the finest
silt particles, to form one lineal inch. The clay particles are
often smaller and of such a nature that they cannot be accurately
measured. The total number of soil particles in even a small
quantity of cultivated soil is far beyond the ordinary limits of
thought, ranging from 125,000 particles of coarse sand to
15,625,000,000,000 particles of the finest silt in one cubic inch.
In other words, if all the particles in one cubic inch of soil
consisting of fine silt were placed side by side, they would form a
continuous chain over a thousand miles long. The farmer, when he
tills the soil, deals with countless numbers of individual soil
grains, far surpassing the understanding of the human mind. It is
the immense number of constituent soil particles that gives to the
soil many of its most valuable properties.
It must be remembered that no natural soil is made up of particles
all of which are of the same size; all sizes, from the coarsest sand
to the finest clay, are usually present. These particles of all
sizes are not arranged in the soil in a regular, orderly way; they
are not placed side by side with geometrical regularity; they are
rather jumbled together in every possible way. The larger sand
grains touch and form comparatively large interstitial spaces into
which the finer silt and clay grains filter. Then, again, the clay
particles, which have cementing properties, bind, as it were, one
particle to another. A sand grain may have attached to it hundreds,
or it may be thousands, of the smaller silt grains; or a regiment of
smaller soil grains may themselves be clustered into one large grain
by cementing power of the clay. Further, in the presence of lime and
similar substances, these complex soil grains are grouped into yet
larger and more complex groups. The beneficial effect of lime is
usually due to this power of grouping untold numbers of soil
particles into larger groups. When by correct soil culture the
individual soil grains are thus grouped into large clusters, the
soil is said to be in good tilth. Anything that tends to destroy
these complex soil grains, as, for instance, plowing the soil when
it is too wet, weakens the crop-producing power of the soil. This
complexity of structure is one of the chief reasons for the
difficulty of understanding clearly the physical laws governing
soils.
Pore-space of soils
It follows from this description of soil structure that the soil
grains do not fill the whole of the soil space. The tendency is
rather to form clusters of soil grains which, though touching at
many points, leave comparatively large empty spaces. This pore space
in soils varies greatly, but with a maximum of about 55 per cent. In
soils formed under arid conditions the percentage of pore-space is
somewhere in the neighborhood of 50 per cent. There are some arid
soils, notably gypsum soils, the particles of which are so uniform
size that the pore-space is exceedingly small. Such soils are always
difficult to prepare for agricultural purposes.
It is the pore-space in soils that permits the storage of
soil-moisture; and it is always important for the farmer so to
maintain his soil that the pore-space is large enough to give him
the best results, not only for the storage of moisture, but for the
growth and development of roots, and for the entrance into the soil
of air, germ life, and other forces that aid in making the soil fit
for the habitation of plants. This can always be best accomplished,
as will be shown hereafter, by deep plowing, when the soil is not
too wet, the exposure of the plowed soil to the elements, the
frequent cultivation of the soil through the growing season, and the
admixture of organic matter. The natural soil structure at depths
not reached by the plow evidently cannot be vitally changed by the
farmer.
Hygroscopic soil-water
Under normal conditions, a certain amount of water is always found
in all things occurring naturally, soils included. Clinging to every
tree, stone, or animal tissue is a small quantity of moisture
varying with the temperature, the amount of water in the air, and
with other well-known factors. It is impossible to rid any natural
substance wholly of water without heating it to a high temperature.
This water which, apparently, belongs to all natural objects is
commonly called hygroscopic water. Hilgard states that the soils of
the arid regions contain, under a temperature of 15 deg C. and an
atmosphere saturated with water, approximately 5-1/2 per cent of
hygroscopic water. In fact, however, the air over the arid region is
far from being saturated with water and the temperature is even
higher than 15 deg C., and the hygroscopic moisture actually found
in the soils of the dry-farm territory is considerably smaller than
the average above given. Under the conditions prevailing in the
Great Basin the hygroscopic water of soils varies from .75 per cent
to 3-1/2 per cent; the average amount is not far from 12 per cent.
Whether or not the hygroscopic water of soils is of value in plant
growth is a disputed question. Hilgard believes that the hygroscopic
moisture can be of considerable help in carrying plants through
rainless summers, and further, that its presence prevents the
heating of the soil particles to a point dangerous to plant roots.
Other authorities maintain earnestly that the hygroscopic soil-water
is practically useless to plants. Considering the fact that wilting
occurs long before the hygroscopic water contained in the soil is
reached, it is very unlikely that water so held is of any real
benefit to plant growth.
Gravitational water
It often happens that a portion of the water in the soil is under
the immediate influence of gravitation. For instance, a stone which,
normally, is covered with hygroscopic water is dipped into water The
hydroscopic water is not thereby affected, but as the stone is drawn
out of the water a good part of the water runs off. This is
gravitational water That is, the gravitational water of soils is
that portion of the soil-water which filling the soil pores, flows
downward through the soil under the influence of gravity. When the
soil pores are completely filled, the maximum amount of
gravitational water is found there. In ordinary dry-farm soils this
total water capacity is between 35 and 40 per cent of the dry weight
of soil.
The gravitational soil-water cannot long remain in that condition;
for, necessarily, the pull of gravity moves it downward through the
soil pores and if conditions are favorable, it finally reaches the
standing water-table, whence it is carried to the great rivers, and
finally to the ocean. In humid soils, under a large precipitation,
gravitational water moves down to the standing water-table after
every rain. In dry-farm soils the gravitational water seldom reaches
the standing water-table; for, as it moves downward, it wets the
soil grains and remains in the capillary condition as a thin film
around the soil grains.
To the dry-farmer, the full water capacity is of importance only as
it pertains to the upper foot of soil. If, by proper plowing and
cultivation, the upper soil be loose and porous, the precipitation
is allowed to soak quickly into the soil, away from the action of
the wind and sun. From this temporary reservoir, the water, in
obedience to the pull of gravity, will move slowly downward to the
greater soil depths, where it will be stored permanently until
needed by plants. It is for this reason that dry-farmers find it
profitable to plow in the fall, as soon as possible after
harvesting. In fact, Campbell advocates that the harvester be
followed immediately by the disk, later to be followed by the plow
The essential thing is to keep the topsoil open and receptive to a
rain.
Capillary soil-water
The so-called capillary soil-water is of greatest importance to the
dry-farmer. This is the water that clings as a film around a marble
that has been dipped into water. There is a natural attraction
between water and nearly all known substances, as is witnessed by
the fact that nearly all things may be moistened. The water is held
around the marble because the attraction between the marble and the
water is greater than the pull of gravity upon the water. The
greater the attraction, the thicker the film; the smaller the
attraction, the thinner the film will be. The water that rises in a
capillary glass tube when placed in water does so by virtue of the
attraction between water and glass. Frequently, the force that makes
capillary water possible is called surface tension.
Whenever there is a sufficient amount of water available, a thin
film of water is found around every soil grain; and where the soil
grains touch, or where they are very near together, water is held
pretty much as in capillary tubes. Not only are the soil particles
enveloped by such a film, but the plant roots foraging in the soil
are likewise covered; that is, the whole system of soil grains and
roots is covered, under favorable conditions, with a thin film of
capillary water. It is the water in this form upon which plants draw
during their periods of growth. The hygroscopic water and the
gravitational water are of comparatively little value in plant
growth.
Field capacity of soils for capillary water
The tremendously large number of soil grains found in even a small
amount of soil makes it possible for the soil to hold very large
quantities of capillary water. To illustrate: In one cubic inch of
sand soil the total surface exposed by the soil grains varies from
42 square inches to 27 square feet; in one cubic inch of silt soil,
from 27 square feet to 72 square feet, and in one cubic inch of an
ordinary soil the total surface exposed by the soil grains is about
25 square feet. This means that the total surface of the soil grains
contained in a column of soil 1 square foot at the top and 10 feet
deep is approximately 10 acres. When even a thin film of water is
spread over such a large area, it is clear that the total amount of
water involved must be large It is to be noticed, therefore, that
the fineness of the soil particles previously discussed has a direct
bearing upon the amount of water that soils may retain for the use
of plant growth. As the fineness of the soil grains increases, the
total surface increases' and the water-holding capacity also
increases.
Naturally, the thickness of a water film held around the soil grains
is very minute. King has calculated that a film 275 millionths of an
inch thick, clinging around the soil particles, is equivalent to
14.24 per cent of water in a heavy clay; 7.2 per cent in a loam;
5.21 per cent in a sandy loam, and 1.41 per cent in a sandy soil.
It is important to know the largest amount of water that soils can
hold in a capillary condition, for upon it depend, in a measure, the
possibilities of crop production under dry-farming conditions. King
states that the largest amount of capillary water that can be held
in sandy loams varies from 17.65 per cent to 10.67 per cent; in clay
loams from 22.67 per cent to 18.16 per cent, and in humus soils
(which are practically unknown in dry-farm sections) from 44.72 per
cent to 21.29 per cent. These results were not obtained under
dry-farm conditions and must be confirmed by investigations of arid
soils.
The water that falls upon dry-farms is very seldom sufficient in
quantity to reach the standing water-table, and it is necessary,
therefore, to determine the largest percentage of water that a soil
can hold under the influence of gravity down to a depth of 8 or 10
feet--the depth to which the roots penetrate and in which root
action is distinctly felt. This is somewhat difficult to determine
because the many conflicting factors acting upon the soil-water are
seldom in equilibrium. Moreover, a considerable time must usually
elapse before the rain-water is thoroughly distributed throughout
the soil. For instance, in sandy soils, the downward descent of
water is very rapid; in clay soils, where the preponderance of fine
particles makes minute soil pores, there is considerable hindrance
to the descent of water, and it may take weeks or months for
equilibrium to be established. It is believed that in a dry-farm
district, where the major part of the precipitation comes during
winter, the early springtime, before the spring rains come, is the
best time for determining the maximum water capacity of a soil. At
that season the water-dissipating influences, such as sunshine and
high temperature, are at a minimum, and a sufficient time has
elapsed to permit the rains of fall and winter to distribute
themselves uniformly throughout the soil. In districts of high
summer precipitation, the late fall after a fallow season will
probably be the best time for the determination of the field-water
capacity.
Experiments on this subject have been conducted at the Utah Station.
As a result of several thousand trials it was found that, in the
spring, a uniform, sandy loam soil of true arid properties
contained, from year to year, an average of nearly 16-1/2 per cent
of water to a depth of 8 feet. This appeared to be practically the
maximum water capacity of that soil under field conditions, and it
may be called the field capacity of that soil for capillary water.
Other experiments on dry-farms showed the field capacity of a clay
soil to a depth of 8 feet to be 19 per cent; of a clay loam, to be
18 per cent; of a loam, 17 per cent; of another loam somewhat more
sandy, 16 per cent; of a sandy loam, 14-1/2 per cent; and of a very
sandy loam, 14 per cent. Leather found that in the calcareous arid
soil of India the upper 5 feet contained 18 per cent of water at the
close of the wet season.
It may be concluded, therefore, that the field-water capacities of
ordinary dry-farm soils are not very high, ranging from 15 to 20 per
cent, with an average for ordinary dry-farm soils in the
neighborhood of 16 or 17 per cent. Expressed in another way this
means that a layer of water from 2 to 3 inches deep can be stored in
the soil to a depth of 12 inches. Sandy soils will hold less water
than clayey ones. It must not be forgotten that in the dry-farm
region are numerous types of soils, among them some consisting
chiefly of very fine soil grains and which would; consequently,
possess field-water capacities above the average here stated. The
first endeavor of the dry-farmer should be to have the soil filled
to its full field-water capacity before a crop is planted.
Downward movement of soil-moisture
One of the chief considerations in a discussion of the storing of
water in soils is the depth to which water may move under ordinary
dry-farm conditions. In humid regions, where the water table is near
the surface and where the rainfall is very abundant, no question has
been raised concerning the possibility of the descent of water
through the soil to the standing water. Considerable objection,
however, has been offered to the doctrine that the rainfall of arid
districts penetrates the soil to any great extent. Numerous writers
on the subject intimate that the rainfall under dry-farm conditions
reaches at the best the upper 3 or 4 feet of soil. This cannot be
true, for the deep rich soils of the arid region, which never have
been disturbed by the husbandman, are moist to very great depths. In
the deserts of the Great Basin, where vegetation is very scanty,
soil borings made almost anywhere will reveal the fact that moisture
exists in considerable quantities to the full depth of the ordinary
soil auger, usually 10 feet. The same is true for practically every
district of the arid region.
Such water has not come from below, for in the majority of cases the
standing water is 50 to 500 feet below the surface. Whitney made
this observation many years ago and reported it as a striking
feature of agriculture in arid regions, worthy of serious
consideration. Investigations made at the Utah Station have shown
that undisturbed soils within the Great Basin frequently contain, to
a depth of 10 feet, an amount of water equivalent to 2 or 3 years of
the rainfall which normally occurs in that locality. These
quantities of water could not be found in such soils, unless, under
arid conditions, water has the power to move downward to
considerably greater depths than is usually believed by dry-farmers.
In a series of irrigation experiments conducted at the Utah Station
it was demonstrated that on a loam soil, within a few hours after an
irrigation, some of the water applied had reached the eighth foot,
or at least had increased the percentage of water in the eighth
foot. In soil that was already well filled with water, the addition
of water was felt distinctly to the full depth of 8 feet. Moreover,
it was observed in these experiments that even very small rains
caused moisture changes to considerable depths a few hours after the
rain was over. For instance, 0.14 of an inch of rainfall was felt to
a depth of 2 feet within 3 hours; 0.93 of an inch was felt to a
depth of 3 feet within the same period.
To determine whether or not the natural winter precipitation, upon
which the crops of a large portion of the dry-farm territory depend,
penetrates the soil to any great depth a series of tests were
undertaken. At the close of the harvest in August or September the
soil was carefully sampled to a depth of 8 feet, and in the
following spring similar samples were taken on the same soils to the
same depth. In every case, it was found that the winter
precipitation had caused moisture changes to the full depth reached
by the soil auger. Moreover, these changes were so great as to lead
the investigators to believe that moisture changes had occurred to
greater depths.
In districts where the major part of the precipitation occurs during
the summer the same law is undoubtedly in operation; but, since
evaporation is most active in the summer, it is probable that a
smaller proportion reaches the greater soil depths. In the Great
Plains district, therefore, greater care will have to be exercised
during the summer in securing proper water storage than in the Great
Basin, for instance. The principle is, nevertheless, the same. Burr,
working under Great Plains conditions in Nebraska, has shown that
the spring and summer rains penetrate the soil to the depth of 6
feet, the average depth of the borings, and that it undoubtedly
affects the soil-moisture to the depth of 10 feet. In general, the
dry-farmer may safely accept the doctrine that the water that falls
upon his land penetrates the soil far beyond the immediate reach of
the sun, though not so far away that plant roots cannot make use of
it.
Importance of a moist subsoil
In the consideration of the downward movement of soil-water it is to
be noted that it is only when the soil is tolerably moist that the
natural precipitation moves rapidly and freely to the deeper soil
layers. When the soil is dry, the downward movement of the water is
much slower and the bulk of the water is then stored near the
surface where the loss of moisture goes on most rapidly. It has been
observed repeatedly in the investigations at the Utah Station that
when desert land is broken for dry-farm purposes and then properly
cultivated, the precipitation penetrates farther and farther into
the soil with every year of cultivation. For example, on a dry-farm,
the soil of which is clay loam, and which was plowed in the fall of
1904 and farmed annually thereafter, the eighth foot contained in
the spring of 1905, 6.59 per cent of moisture; in the spring of
1906, 13.11 per cent, and in the spring of 1907, 14.75 per cent of
moisture. On another farm, with a very sandy soil and also plowed in
the fall of 1904, there was found in the eighth foot in the spring
of 1905, 5.63 per cent of moisture, in the spring of 1906, 11.41 per
cent of moisture, and in the spring of 1907, 15.49 per cent of
moisture. In both of these typical cases it is evident that as the
topsoil was loosened, the full field water capacity of the soil was
more nearly approached to a greater depth. It would seem that, as
the lower soil layers are moistened, the water is enabled, so to
speak, to slide down more easily into the depths of the soil.
This is a very important principle for the dry farmer to understand.
It is always dangerous to permit the soil of a dry-farm to become
very dry, especially below the first foot. Dry-farms should be so
manipulated that even at the harvesting season a comparatively large
quantity of water remains in the soil to a depth of 8 feet or more.
The larger the quantity of water in the soil in the fall, the more
readily and quickly will the water that falls on the land during the
resting period of fall, winter, and early spring sink into the soil
and move away from the topsoil. The top or first foot will always
contain the largest percentage of water because it is the chief
receptacle of the water that falls as rain or snow but when the
subsoil is properly moist, the water will more completely leave the
topsoil. Further, crops planted on a soil saturated with water to a
depth of 8 feet are almost certain to mature and yield well.
If the field-water capacity has not been filled, there is always the
danger that an unusually dry season or a series of hot winds or
other like circumstances may either seriously injure the crop or
cause a complete failure. The dry-farmer should keep a surplus of
moisture in the soil to be carried over from year to year, just as
the wise business man maintains a sufficient working capital for the
needs of his business. In fact, it is often safe to advise the
prospective dry-farmer to plow his newly cleared or broken land
carefully and then to grow no crop on it the first year, so that,
when crop production begins, the soil will have stored in it an
amount of water sufficient to carry a crop over periods of drouth.
Especially in districts of very low rainfall is this practice to be
recommended. In the Great Plains area, where the summer rains tempt
the farmer to give less attention to the soil-moisture problem than
in the dry districts with winter precipitation farther West, it is
important that a fallow season be occasionally given the land to
prevent the store of soil moisture from becoming dangerously low.
To what extent is the rainfall stored in soils?
What proportion of the actual amount of water falling upon the soil
can be stored in the soil and carried over from season to season?
This question naturally arises in view of the conclusion that water
penetrates the soil to considerable depths. There is comparatively
little available information with which to answer this question,
because the great majority of students of soil moisture have
concerned themselves wholly with the upper two, three, or four feet
of soil. The results of such investigations are practically useless
in answering this question. In humid regions it may be very
satisfactory to confine soil-moisture investigations to the upper
few feet; but in arid regions, where dry-farming is a living
question, such a method leads to erroneous or incomplete
conclusions.
Since the average field capacity of soils for water is about 2.5
inches per foot, it follows that it is possible to store 25 inches
of water in 10 feet of soil. This is from two to one and a half
times one year's rainfall over the better dry-farming sections.
Theoretically, therefore, there is no reason why the rainfall of one
season or more could not be stored in the soil. Careful
investigations have borne out this theory. Atkinson found, for
example, at the Montana Station, that soil, which to a depth of 9
feet contained 7.7 per cent of moisture in the fall contained 11.5
per cent in the spring and, after carrying it through the summer by
proper methods of cultivation, 11 per cent.
It may certainly be concluded from this experiment that it is
possible to carry over the soil moisture from season to season. The
elaborate investigations at the Utah Station have demonstrated that
the winter precipitation, that is, the precipitation that comes
during the wettest period of the year, may be retained in a large
measure in the soil. Naturally, the amount of the natural
precipitation accounted for in the upper eight feet will depend upon
the dryness of the soil at the time the investigation commenced. If
at the beginning of the wet season the upper eight feet of soil are
fairly well stored with moisture, the precipitation will move down
to even greater depths, beyond the reach of the soil auger. If, on
the other hand, the soil is comparatively dry at the beginning of
the season, the natural precipitation will distribute itself through
the upper few feet, and thus be readily measured by the soil auger.
In the Utah investigations it was found that of the water which fell
as rain and snow during the winter, as high as 95-1/2 per cent was
found stored in the first eight feet of soil at the beginning of the
growing season. Naturally, much smaller percentages were also found,
but on an average, in soils somewhat dry at the beginning of the dry
season, more than three fourths of the natural precipitation was
found stored in the soil in the spring. The results were all
obtained in a locality where the bulk of the precipitation comes in
the winter, yet similar results would undoubtedly be obtained where
the precipitation occurs mainly in the summer. The storage of water
in the soil cannot be a whit less important on the Great Plains than
in the Great Basin. In fact, Burr has clearly demonstrated for
western Nebraska that over 50 per cent of the rainfall of the spring
and summer may be stored in the soil to the depth of six feet.
Without question, some is stored also at greater depths.
All the evidence at hand shows that a large portion of the
precipitation falling upon properly prepared soil, whether it be
summer or winter, is stored in the soil until evaporation is allowed
to withdraw it Whether or not water so stored may be made to remain
in the soil throughout the season or the year will be discussed in
the next chapter. It must be said, however, that the possibility of
storing water in the soil, that is, making the water descend to
relatively great soil depths away from the immediate and direct
action of the sunshine and winds, is the most fundamental principle
in successful dry-farming.
The fallow
It may be safely concluded that a large portion of the water that
falls as rain or snow may be stored in the soil to considerable
depths (eight feet or more). However, the question remains, Is it
possible to store the rainfall of successive years in the soil for
the use of one crop? In short, Does the practice of clean fallowing
or resting the ground with proper cultivation for one season enable
the farmer to store in the soil the larger portion of the rainfall
of two years, to be used for one crop? It is unquestionably true, as
will be shown later, that clean fallowing or "summer tillage" is one
of the oldest and safest practices of dry-farming as practiced in
the West, but it is not generally understood why fallowing is
desirable.
Considerable doubt has recently been cast upon the doctrine that one
of the beneficial effects of fallowing in dry-farming is to store
the rainfall of successive seasons in the soil for the use of one
crop. Since it has been shown that a large proportion of the winter
precipitation can be stored in the soil during the wet season, it
merely becomes a question of the possibility of preventing the
evaporation of this water during the drier season. As will be shown
in the next chapter, this can well be effected by proper
cultivation.
There is no good reason, therefore, for believing that the
precipitation of successive seasons may not be added to water
already stored in the soil. King has shown that fallowing the soil
one year carried over per square foot, in the upper four feet, 9.38
pounds of water more than was found in a cropped soil in a parallel
experiment; and, moreover, the beneficial effect of this. water
advantage was felt for a whole succeeding season. King concludes,
therefore, that one of the advantages of fallowing is to increase
the moisture content of the soil. The Utah experiments show that the
tendency of fallowing is always to increase the soil-moisture
content. In dry-farming, water is the critical factor, and any
practice that helps to conserve water should be adopted. For that
reason, fallowing, which gathers soil-moisture, should be strongly
advocated. In Chapter IX another important value of the fallow will
be discussed.
In view of the discussion in this chapter it is easily understood
why students of soil-moisture have not found a material increase in
soil-moisture due to fallowing. Usually such investigations have
been made to shallow depths which already were fairly well filled
with moisture. Water falling upon such soils would sink beyond the
depth reached by the soil augers, and it became impossible to judge
accurately of the moisture-storing advantage of the fallow. A
critical analysis of the literature on this subject will reveal the
weakness of most experiments in this respect.
It may be mentioned here that the only fallow that should be
practiced by the dry-farmer is the clean fallow. Water storage is
manifestly impossible when crops are growing upon a soil. A healthy
crop of sagebrush, sunflowers, or other weeds consumes as much water
as a first-class stand of corn, wheat, or potatoes. Weeds should be
abhorred by the farmer. A weedy fallow is a sure forerunner of a
crop failure. How to maintain a good fallow is discussed in Chapter
VIII, under the head of Cultivation. Moreover, the practice of
fallowing should be varied with the climatic conditions. In
districts of low rainfall, 10-15 inches, the land should be clean
summer-fallowed every other year; under very low rainfall perhaps
even two out of three years; in districts of more abundant rainfall,
15-20 inches, perhaps one year out of every three or four is
sufficient. Where the precipitation comes during the growing season,
as in the Great Plains area, fallowing for the storage of water is
less important than where the major part of the rainfall comes
during the fall and winter. However, any system of dry-farming that
omits fallowing wholly from its practices is in danger of failure in
dry years.
Deep plowing for water storage
It has been attempted in this chapter to demonstrate that water
falling upon a soil may descend to great depths, and may be stored
in the soil from year to year, subject to the needs of the crop that
may be planted. By what cultural treatment may this downward descent
of the water be accelerated by the farmer? First and foremost, by
plowing at the right time and to the right depth. Plowing should be
done deeply and thoroughly so that the falling water may immediately
be drawn down to the full depth of the loose, spongy, plowed soil,
away from the action of the sunshine or winds. The moisture thus
caught will slowly work its way down into the lower layers of the
soil. Deep plowing is always to be recommended for successful
dry-farming.
In humid districts where there is a great difference between the
soil and the subsoil, it is often dangerous to turn up the lifeless
subsoil, but in arid districts where there is no real
differentiation between the soil and the subsoil, deep plowing may
safely be recommended. True, occasionally, soils are found in the
dry-farm territory which are underlaid near the surface by an inert
clay or infertile layer of lime or gypsum which forbids the farmer
putting the plow too deeply into the soil. Such soils, however' are
seldom worth while trying for dry-farm purposes. Deep plowing must
be practiced for the best dry-farming results.
It naturally follows that subsoiling should be a beneficial practice
on dry-farms. Whether or not the great cost of subsoiling is offset
by the resulting increased yields is an open question; it is, in
fact, quite doubtful. Deep plowing done at the right time and
frequently enough is possibly sufficient. By deep plowing is meant
stirring or turning the soil to a depth of six to ten inches below
the surface of the land.
Fall plowing far water storage
It is not alone sufficient to plow and to plow deeply; it is also
necessary that the plowing be done at the right time. In the very
great majority of cases over the whole dry-farm territory, plowing
should be done in the fall. There are three reasons for this: First,
after the crop is harvested, the soil should be stirred immediately,
so that it can be exposed to the full action of the weathering
agencies, whether the winters be open or closed. If for any reason
plowing cannot be done early it is often advantageous to follow the
harvester with a disk and to plow later when convenient. The
chemical effect on the soil resulting from the weathering, made
possible by fall plowing, as will be shown in Chapter IX, is of
itself so great as to warrant the teaching of the general practice
of fall plowing. Secondly, the early stirring of the soil prevents
evaporation of the moisture in the soil during late summer and the
fall. Thirdly, in the parts of the dry-farm territory where much
precipitation occurs in the fall, winter, or early spring, fall
plowing permits much of this precipitation to enter the soil and be
stored there until needed by plants.
A number of experiment stations have compared plowing done in the
early fall with plowing done late in the fall or in the spring, and
with almost no exception it has been found that early fall plowing
is water-conserving and in other ways advantageous. It was observed
on a Utah dry-farm that the fall-plowed land contained, to a depth
of 10 feet, 7.47 acre-inches more water than the adjoining
spring-plowed land--a saving of nearly one half of a year's
precipitation. The ground should be plowed in the early fall as soon
as possible after the crop is harvested. It should then be left in
the rough throughout the winter, so that it may be mellowed and
broken down by the elements. The rough lend further has a tendency
to catch and hold the snow that may be blown by the wind, thus
insuring a more even distribution of the water from the melting
snow.
A common objection to fall plowing is that the ground is so dry in
the fall that it does not plow up well, and that the great dry clods
of earth do much to injure the physical condition of the soil. It is
very doubtful if such an objection is generally valid, especially if
the soil is so cropped as to leave a fair margin of moisture in the
soil at harvest time. The atmospheric agencies will usually break
down the clods, and the physical result of the treatment will be
beneficial. Undoubtedly, the fall plowing of dry land is somewhat
difficult, but the good results more than pay the farmer for his
trouble. Late fall plowing, after the fall rains have softened the
land, is preferable to spring plowing. If for any reason the farmer
feels that he must practice spring plowing, he should do it as early
as possible in the spring. Of course, it is inadvisable to plow the
soil when it is so wet as to injure its tilth seriously, but as soon
as that danger period has passed, the plow should be placed in the
ground. The moisture in the soil will thereby be conserved, and
whatever water may fall during the spring months will be conserved
also. This is of especial importance in the Great Plains region and
in any district where the precipitation comes in the spring and
winter months.
Likewise, after fall plowing, the land must be well stirred in the
early spring with the disk harrow or a similar implement, to enable
the spring rains to enter the soil easily and to prevent the
evaporation of the water already stored. Where the rainfall is quite
abundant and the plowed land has been beaten down by the frequent
rains, the land should be plowed again in the spring. Where such
conditions do not exist, the treatment of the soil with the disk and
harrow in the spring is usually sufficient.
In recent dry-farm experience it has been fairly completely
demonstrated that, providing the soil is well stored with water,
crops will mature even if no rain falls during the growing season.
Naturally, under most circumstances, any rains that may fall on a
well-prepared soil during the season of crop growth will tend to
increase the crop yield, but some profitable yield is assured, in
spite of the season, if the soil is well stored with water at seed
time. This is an important principle in the system of dry-farming.
CHAPTER VIII
REGULATING THE EVAPORATION
The demonstration in the last chapter that the water which falls as
rain or snow may be stored in the soil for the use of plants is of
first importance in dry-farming, for it makes the farmer
independent, in a large measure, of the distribution of the
rainfall. The dry-farmer who goes into the summer with a soil well
stored with water cares little whether summer rains come or not, for
he knows that his crops will mature in spite of external drouth. In
fact, as will be shown later, in many dry-farm sections where the
summer rains are light they are a positive detriment to the farmer
who by careful farming has stored his deep soil with an abundance of
water. Storing the soil with water is, however, only the first step
in making the rains of fall, winter, or the preceding year available
for plant growth. As soon as warm growing weather comes,
water-dissipating forces come into play, and water is lost by
evaporation. The farmer must, therefore, use all precautions to keep
the moisture in the soil until such time as the roots of the crop
may draw it into the plants to be used in plant production. That is,
as far as possible, direct evaporation of water from the soil must
be prevented.
Few farmers really realize the immense possible annual evaporation
in the dry-farm territory. It is always much larger than the total
annual rainfall. In fact, an arid region may be defined as one in
which under natural conditions several times more water evaporates
annually from a free water surface than falls as rain and snow. For
that reason many students of aridity pay little attention to
temperature, relative humidity, or winds, and simply measure the
evaporation from a free water surface in the locality in question.
In order to obtain a measure of the aridity, MacDougal has
constructed the following table, showing the annual precipitation
and the annual evaporation at several well-known localities in the
dry-farm territory.
True, the localities included in the following table are extreme,
but they illustrate the large possible evaporation, ranging from
about six to thirty-five times the precipitation. At the same time
it must be borne in mind that while such rates of evaporation may
occur from free water surfaces, the evaporation from agricultural
soils under like conditions is very much smaller.
Place Annual Precipitation Annual Evaporation Ratio
(In Inches) (In Inches)
El Paso, Texas 9.23 80 8.7
Fort Wingate,
New Mexico 14.00 80 5.7
Fort Yuma,
Arizona 2.84 100 35.2
Tucson, AZ 11.74 90 7.7
Mohave, CA 4.97 95 19.1
Hawthorne,
Nevada 4.50 80 17.5
Winnemucca,
Nevada 9.51 80 9.6
St. George, Utah 6.46 90 13.9
Fort Duchesne,
Utah 6.49 75 11.6
Pineville,
Oregon 9.01 70 7.8
Lost River,
Idaho 8.47 70 8.3
Laramie,
Wyoming 9.81 70 7.1
Torres, Mexico 16.97 100 6.0
To understand the methods employed for checking evaporation from the
soil, it is necessary to review briefly the conditions that
determine the evaporation of water into the air, and the manner in
which water moves in the soil.
The formation of water vapor
Whenever water is left freely exposed to the air, it evaporates;
that is, it passes into the gaseous state and mixes with the gases
of the air. Even snow and ice give off water vapor, though in very
small quantities. The quantity of water vapor which can enter a
given volume of air is definitely limited. For instance, at the
temperature of freezing water 2.126 grains of water vapor can enter
one cubic foot of air, but no more. When air contains all the water
possible, it is said to be saturated, and evaporation then ceases.
The practical effect of this is the well-known experience that on
the seashore, where the air is often very nearly fully saturated
with water vapor, the drying of clothes goes on very slowly, whereas
in the interior, like the dry-farming territory, away from the
ocean, where the air is far from being saturated, drying goes on
very rapidly.
The amount of water necessary to saturate air varies greatly with
the temperature. It is to be noted that as the temperature
increases, the amount of water that may be held by the air also
increases; and proportionately more rapidly than the increase in
temperature. This is generally well understood in common experience,
as in drying clothes rapidly by hanging them before a hot fire. At a
temperature of 100 deg F., which is often reached in portions of the
dry-farm territory during the growing season, a given volume of air
can hold more than nine times as much water vapor as at the
temperature of freezing water. This is an exceedingly important
principle in dry-farm practices, for it explains the relatively easy
possibility of storing water during the fall and winter when the
temperature is low and the moisture usually abundant, and the
greater difficulty of storing the rain that falls largely, as in the
Great Plains area, in the summer when water-dissipating forces are
very active. This law also emphasizes the truth that it is in times
of warm weather that every precaution must be taken to prevent the
evaporation of water from the soil surface.
Temperature Grains of Water held in
in Degrees F. One Cubic Foot of Air
32 2.126
40 2.862
50 4.089
60 5.756
70 7.992
80 10.949
90 14.810
100 19.790
It is of course well understood that the atmosphere as a whole is
never saturated with water vapor. Such saturation is at the best
only local, as, for instance, on the seashore during quiet days,
when the layer of air over the water may be fully saturated, or in a
field containing much water from which, on quiet warm days, enough
water may evaporate to saturate the layer of air immediately upon
the soil and around the plants. Whenever, in such cases, the air
begins to move and the wind blows, the saturated air is mixed with
the larger portion of unsaturated air, and evaporation is again
increased. Meanwhile, it must be borne in mind that into a layer of
saturated air resting upon a field of growing plants very little
water evaporates, and that the chief water-dissipating power of
winds lies in the removal of this saturated layer. Winds or air
movements of any kind, therefore, become enemies of the farmer who
depends upon a limited rainfall.
The amount of water actually found in a given volume of air at a
certain temperature, compared with the largest amount it can hold,
is called the relative humidity of the air. As shown in Chapter IV,
the relative humidity becomes smaller as the rainfall decreases. The
lower the relative humidity is at a given temperature, the more
rapidly will water evaporate into the air. There is no more striking
confirmation of this law than the fact that at a temperature of 90
deg sunstrokes and similar ailments are reported in great number
from New York, while the people of Salt Lake City are perfectly
comfortable. In New York the relative humidity in summer is about 73
per cent; in Salt Lake City, about 35 per cent. At a high summer
temperature evaporation from the skin goes on slowly in New York and
rapidly in Salt Lake City, with the resulting discomfort or comfort.
Similarly, evaporation from soils goes on rapidly under a low and
slowly under a high percentage of relative humidity.
Evaporation from water surfaces is hastened, therefore, by (1) an
increase in the temperature, (2) an increase in the air movements or
winds, and (3) a decrease in the relative humidity. The temperature
is higher; the relative humidity lower, and the winds usually more
abundant in arid than in humid regions. The dry-farmer must
consequently use all possible precautions to prevent evaporation
from the soil.
Conditions of evaporation from from soils
Evaporation does not alone occur from a surface of free water. All
wet or moist substances lose by evaporation most of the water that
they hold, providing the conditions of temperature and relative
humidity are favorable. Thus, from a wet soil, evaporation is
continually removing water. Yet, under ordinary conditions, it is
impossible to remove all the water, for a small quantity is
attracted so strongly by the soil particles that only a temperature
above the boiling point of water will drive it out. This part of the
soil is the hygroscopic moisture spoken of in the last chapter.
Moreover, it must be kept in mind that evaporation does not occur as
rapidly from wet soil as from a water surface, unless all the soil
pores are so completely filled with water that the soil surface is
practically a water surface. The reason for this reduced evaporation
from a wet soil is almost self-evident. There is a comparatively
strong attraction between soil and water, which enables the moisture
to cling as a thin capillary film around the soil particles, against
the force of gravity. Ordinarily, only capillary water is found in
well-tilled soil, and the force causing evaporation must be strong
enough to overcome this attraction besides changing the water into
vapor.
The less water there is in a soil, the thinner the water film, and
the more firmly is the water held. Hence, the rate of evaporation
decreases with the decrease in soil-moisture. This law is confirmed
by actual field tests. For instance, as an average of 274 trials
made at the Utah Station, it was found that three soils, otherwise
alike, that contained, respectively, 22.63 per cent, 17.14 per cent,
and 12.75 per cent of water lost in two weeks, to a depth of eight
feet, respectively 21.0, 17. 1, and 10.0 pounds of water per square
foot. Similar experiments conducted elsewhere also furnish proof of
the correctness of this principle. From this point of view the
dry-farmer does not want his soils to be unnecessarily moist. The
dry-farmer can reduce the per cent of water in the soil without
diminishing the total amount of water by so treating the soil that
the water will distribute itself to considerable depths. This brings
into prominence again the practices of fall plowing, deep plowing,
subsoiling, and the choice of deep soils for dry-farming.
Very much for the same reasons, evaporation goes on more slowly from
water in which salt or other substances have been dissolved. The
attraction between the water and the dissolved salt seems to be
strong enough to resist partially the force causing evaporation.
Soil-water always contains some of the soil ingredients in solution,
and consequently under the given conditions evaporation occurs more
slowly from soil-water than from pure water. Now, the more fertile a
soil is, that is, the more soluble plant-food it contains, the more
material will be dissolved in the soil-water, and as a result the
more slowly will evaporation take place. Fallowing, cultivation,
thorough plowing and manuring, which increase the store of soluble
plant-food, all tend to diminish evaporation. While these conditions
may have little value in the eyes of the farmer who is under an
abundant rainfall, they are of great importance to the dry-farmer.
It is only by utilizing every possibility of conserving water and
fertility that dry-farming may be made a perfectly safe practice.
Loss by evaporation chiefly at the surface
Evaporation goes on from every wet substance. Water evaporates
therefore from the wet soil grains under the surface as well as from
those at the surface. In developing a system of practice which will
reduce evaporation to a minimum it must be learned whether the water
which evaporates from the soil particles far below the surface is
carried in large quantities into the atmosphere and thus lost to
plant use. Over forty years ago, Nessler subjected this question to
experiment and found that the loss by evaporation occurs almost
wholly at the soil surface, and that very little if any is lost
directly by evaporation from the lower soil layers. Other
experimenters have confirmed this conclusion, and very recently
Buckingham, examining the same subject, found that while there is a
very slow upward movement of the soil gases into the atmosphere, the
total quantity of the water thus lost by direct evaporation from
soil, a foot below the surface, amounted at most to one inch of
rainfall in six years. This is insignificant even under semiarid and
arid conditions. However, the rate of loss of water by direct
evaporation from the lower soil layers increases with the porosity
of the soil, that is, with the space not filled with soil particles
or water. Fine-grained soils, therefore, lose the least water in
this manner. Nevertheless, if coarse-grained soils are well filled
with water, by deep fall plowing and by proper summer fallowing for
the conservation of moisture, the loss of moisture by direct
evaporation from the lower soil layers need not be larger than from
finer grained soils
Thus again are emphasized the principles previously laid down that,
for the most successful dry-farming, the soil should always be kept
well filled with moisture, even if it means that the land, after
being broken, must lie fallow for one or two seasons, until a
sufficient amount of moisture has accumulated. Further, the
correlative principle is emphasized that the moisture in dry-farm
lands should be stored deeply, away from the immediate action of the
sun's rays upon the land surface. The necessity for deep soils is
thus again brought out.
The great loss of soil moisture due to an accumulation of water in
the upper twelve inches is well brought out in the experiments
conducted by the Utah Station. The following is selected from the
numerous data on the subject. Two soils, almost identical in
character, contained respectively 17.57 per cent and 16.55 per cent
of water on an average to a depth of eight feet; that is, the total
amount of water held by the two soils was practically identical.
Owing to varying cultural treatment, the distribution of the water
in the soil was not uniform; one contained 23.22 per cent and the
other 16.64 per cent of water in the first twelve inches. During the
first seven days the soil that contained the highest percentage of
water in the first foot lost 13.30 pounds of water, while the other
lost only 8.48 pounds per square foot. This great difference was due
no doubt to the fact that direct evaporation takes place in
considerable quantity only in the upper twelve inches of soil, where
the sun's heat has a full chance to act.
Any practice which enables the rains to sink quickly to considerable
depths should be adopted by the dry-farmer. This is perhaps one of
the great reasons for advocating the expensive but usually effective
subsoil plowing on dry-farms. It is a very common experience, in the
arid region, that great, deep cracks form during hot weather. From
the walls of these cracks evaporation goes on, as from the topsoil,
and the passing winds renew the air so that the evaporation may go
on rapidly. The dry-farmer must go over the land as often as needs
be with some implement that will destroy and fill up the cracks that
may have been formed. In a field of growing crops this is often
difficult to do; but it is not impossible that hand hoeing,
expensive as it is, would pay well in the saving of soil moisture
and the consequent increase in crop yield.
How soil water reaches the surface
It may be accepted as an established truth that the direct
evaporation of water from wet soils occurs almost wholly at the
surface. Yet it is well known that evaporation from the soil surface
may continue until the soil-moisture to a depth of eight or ten feet
or more is depleted. This is shown by the following analyses of
dry-farm soil in early spring and midsummer. No attempt was made to
conserve the moisture in the soil:--
Per cent of water in Early spring Midsummer
1st foot 20.84 8.83
2nd foot 20.06 8.87
3rd foot 19.62 11.03
4th foot 18.28 9.59
5th foot 18.70 11.27
6th foot 14.29 11.03
7th foot 14.48 8.95
8th foot 13.83 9.47
Avg 17.51 9.88
In this case water had undoubtedly passed by capillary movement from
the depth of eight feet to a point near the surface where direct
evaporation could occur. As explained in the last chapter, water
which is held as a film around the soil particles is called
capillary water; and it is in the capillary form that water may be
stored in dry-farm soils. Moreover, it is the capillary
soil-moisture alone which is of real value in crop production. This
capillary water tends to distribute itself uniformly throughout the
soil, in accordance with the prevailing conditions and forces. If no
water is removed from the soil, in course of time the distribution
of the soil-water will be such that the thickness of the film at any
point in the soil mass is a direct resultant of the various forces
acting at that particular point. There will then be no appreciable
movement of the soil-moisture. Such a condition is approximated in
late winter or early spring before planting begins. During the
greater part of the year, however, no such quiescent state can
occur, for there are numerous disturbing elements that normally are
active, among which the three most effective are (l) the addition of
water to the soil by rains; (2) the evaporation of water from the
topsoil, due to the more active meteorological factors during
spring, summer, and fall; and (3) the abstraction of water from the
soil by plant roots.
Water, entering the soil, moves downward under the influence of
gravity as gravitational water, until under the attractive influence
of the soil it has been converted into capillary water and adheres
to the soil particles as a film. If the soil were dry, and the film
therefore thin, the rain water would move downward only a short
distance as gravitational water; if the soil were wet, and the film
therefore thick, the water would move down to a greater distance
before being exhausted. If, as is often the case in humid districts,
the soil is saturated, that is, the film is as thick as the
particles can hold, the water would pass right through the soil and
connect with the standing water below. This, of course, is seldom
the case in dry-farm districts. In any soil, excepting one already
saturated, the addition of water will produce a thickening of the
soil-water film to the full descent of the water. This immediately
destroys the conditions of equilibrium formerly existing, for the
moisture is not now uniformly distributed. Consequently a process of
redistribution begins which continues until the nearest approach to
equilibrium is restored. In this process water will pass in every
direction from the wet portion of the soil to the drier; it does not
necessarily mean that water will actually pass from the wet portion
to the drier portion; usually, at the driest point a little water is
drawn from the adjoining point, which in turn draws from the next,
and that from the next, until the redistribution is complete. The
process is very much like stuffing wool into a sack which already is
loosely filled. The new wool does not reach the bottom of the sack,
yet there is more wool in the bottom than there was before.
If a plant-root is actively feeding some distance under the soil
surface, the reverse process occurs. At the feeding point the root
continually abstracts water from the soil grains and thus makes the
film thinner in that locality. This causes a movement of moisture
similar to the one above described, from the wetter portions of the
soil to the portion being dried out by the action of the plant-root.
Soil many feet or even rods distant may assist in supplying such an
active root with moisture. When the thousands of tiny roots sent out
by each plant are recalled. it may well be understood what a
confusion of pulls and counter-pulls upon the soil-moisture exists
in any cultivated soil. In fact, the soil-water film may be viewed
as being in a state of trembling activity, tending to place itself
in full equilibrium with the surrounding contending forces which,
themselves, constantly change. Were it not that the water film held
closely around the soil particles is possessed of extreme mobility,
it would not be possible to meet the demands of the plants upon the
water at comparatively great distances. Even as it is, it frequently
happens that when crops are planted too thickly on dry-farms, the
soil-moisture cannot move quickly enough to the absorbing roots to
maintain plant growth, and crop failure results. Incidentally, this
points to planting that shall be proportional to the moisture
contained by the soil. See Chapter XI.
As the temperature rises in spring, with a decrease in the relative
humidity, and an increase in direct sunshine, evaporation from the
soil surface increases greatly. However, as the topsoil becomes
drier, that is, as the water fihn becomes thinner, there is an
attempt at readjustment, and water moves upward to take the place of
that lost by evaporation. As this continues throughout the season,
the moisture stored eight or ten feet or more below the surface is
gradually brought to the top and evaporated, and thus lost to plant
use.
The effect of rapid top drying of soils
As the water held by soils diminishes, and the water film around the
soil grains becomes thinner, the capillary movement of the
soil-water is retarded. This is easily understood by recalling that
the soil particles have an attraction for water, which is of
definite value, and may be measured by the thickest film that may be
held against gravity. When the film is thinned, it does not diminish
the attraction of the soil for water; it simply results in a
stronger pull upon the water and a firmer holding of the film
against the surfaces of the soil grains. To move soil-water under
such conditions requires the expenditure of more energy than is
necessary for moving water in a saturated or nearly saturated soil.
Under like conditions, therefore, the thinner the soil-water film
the more difficult will be the upward movement of the soil-water and
the slower the evaporation from the topsoil.
As drying goes on, a point is reached at which the capillary
movement of the water wholly ceases. This is probably when little
more than the hygroscopic moisture remains. In fact, very dry soil
and water repel each other. This is shown in the common experience
of driving along a road in summer, immediately after a light shower.
The masses of dust are wetted only on the outside, and as the wheels
pass through them the dry dust is revealed. It is an important fact
that very dry soil furnishes a very effective protection against the
capillary movement of water.
In accordance with the principle above established if the surface
soil could be dried to the point where capillarity is very slow, the
evaporation would be diminished or almost wholly stopped. More than
a quarter of a century ago, Eser showed experimentally that
soil-water may be saved by drying the surface soil rapidly. Under
dry-farm conditions it frequently occurs that the draft upon the
water of the soil is so great that nearly all the water is quickly
and so completely abstracted from the upper few inches of soil that
they are left as an effective protection against further
evaporation. For instance, in localities where hot dry winds are of
common occurrence, the upper layer of soil is sometimes completely
dried before the water in the lower layers can by slow capillary
movement reach the top. The dry soil layer then prevents further
loss of water, and the wind because of its intensity has helped to
conserve the soil-moisture. Similarly in localities where the
relative humidity is low, the sunshine abundant, and the temperature
high, evaporation may go on so rapidly that the lower soil layers
cannot supply the demands made, and the topsoil then dries out so
completely as to form a protective covering against further
evaporation. It is on this principle that the native desert soils of
the United States, untouched by the plow, and the surfaces of which
are sun-baked, are often found to possess large percentages of water
at lower depths. Whitney recorded this observation with considerable
surprise, many years ago, and other observers have found the same
conditions at nearly all points of the arid region. This matter has
been subjected to further study by Buckingham, who placed a variety
of soils under artificially arid and humid conditions. It was found
in every case that, the initial evaporation was greater under arid
conditions, but as the process went on and the topsoil of the arid
soil became dry, more water was lost under humid conditions. For the
whole experimental period, also, more water was lost under humid
conditions. It was notable that the dry protective layer was formed
more slowly on alkali soils, which would point to the inadvisability
of using alkali lands for dry-farm purposes. All in all, however, it
appears "that under very arid conditions a soil automatically
protects itself from drying by the formation of a natural mulch on
the surface."
Naturally, dry-farm soils differ greatly in their power of forming
such a mulch. A heavy clay or a light sandy soil appears to have
less power of such automatic protection than a loamy soil. An
admixture of limestone seems to favor the formation of such a
natural protective mulch. Ordinarily, the farmer can further the
formation of a dry topsoil layer by stirring the soil thoroughly.
This assists the sunshine and the air to evaporate the water very
quickly. Such cultivation is very desirable for other reasons also,
as will soon be discussed. Meanwhile, the water-dissipating forces
of the dry-farm section are not wholly objectionable, for whether
the land be cultivated or not, they tend to hasten the formation of
dry surface layers of soil which guard against excessive
evaporation. It is in moist cloudy weather, when the drying process
is slow, that evaporation causes the greatest losses of
soil-moisture.
The effect of shading
Direct sunshine is, next to temperature, the most active cause of
rapid evaporation from moist soil surfaces. Whenever, therefore,
evaporation is not rapid enough to form a dry protective layer of
topsoil, shading helps materially in reducing surface losses of
soil-water. Under very arid conditions, however, it is questionable
whether in all cases shading has a really beneficial effect, though
under semiarid or sub-humid conditions the benefits derived from
shading are increased largely. Ebermayer showed in 1873 that the
shading due to the forest cover reduced evaporation 62 per cent, and
many experiments since that day have confirmed this conclusion. At
the Utah Station, under arid conditions, it was found that shading a
pot of soil, which otherwise was subjected to water-dissipating
influences, saved 29 per cent of the loss due to evaporation from a
pot which was not shaded. This principle cannot be applied very
greatly in practice, but it points to a somewhat thick planting,
proportioned to the water held by the soil. It also shows a possible
benefit to be derived from the high header straw which is allowed to
stand for several weeks in dry-farm sections where the harvest comes
early and the fall plowing is done late, as in the mountain states.
The high header stubble shades the ground very thoroughly. Thus the
stubble may be made to conserve the soil-moisture in dry-farm
sections, where grain is harvested by the "header" method.
A special case of shading is the mulching of land with straw or
other barnyard litter, or with leaves, as in the forest. Such
mulching reduces evaporation, but only in part, because of its
shading action, since it acts also as a loose top layer of soil
matter breaking communication with the lower soil layers.
Whenever the soil is carefully stirred, as will be described, the
value of shading as a means or checking evaporation disappears
almost entirely. It is only with soils which are tolerably moist at
the surface that shading acts beneficially.
Alfalfa in cultivated rows. This practice is employed to make
possible the growth of alfalfa and other perennial crops on arid
lands without irrigation.
The effect of tillage
Capillary soil-moisture moves from particle to particle until the
surface is reached. The closer the soil grains are packed together,
the greater the number of points or contact, and the more easily
will the movement of the soil-moisture proceed. If by any means a
layer of the soil is so loosened as to reduce the number of points
of contact, the movement of the soil-moisture is correspondingly
hindered. The process is somewhat similar to the experience in large
r airway stations. Just before train time a great crowd of people is
gathered outside or the gates ready to show their tickets. If one
gate is opened, a certain number of passengers can pass through each
minute; if two are opened, nearly twice as many may be admitted in
the same time; if more gates are opened, the passengers will be able
to enter the train more rapidly. The water in the lower layers of
the soil is ready to move upward whenever a call is made upon it. To
reach the surface it must pass from soil grain to soil grain, and
the larger the number of grains that touch, the more quickly and
easily will the water reach the surface, for the points of contact
of the soil particles may be likened to the gates of the railway
station. Now if, by a thorough stirring and loosening of the
topsoil, the number of points of contact between the top and subsoil
is greatly reduced, the upward flow of water is thereby largely
checked. Such a loosening of the topsoil for the purpose of reducing
evaporation from the topsoil has come to be called cultivation, and
includes plowing, harrowing, disking, hoeing, and other cultural
operations by which the topsoil is stirred. The breaking of the
points of contact between the top and subsoil is undoubtedly the
main reason for the efficiency of cultivation, but it is also to be
remembered that such stirring helps to dry the top soil very
thoroughly, and as has been explained a layer of dry soil of itself
is a very effective check upon surface evaporation.
That the stirring or cultivation of the topsoil really does diminish
evaporation of water from the soil has been shown by numerous
investigations. In 1868, Nessler found that during six weeks of an
ordinary German summer a stirred soil lost 510 grams of water per
square foot, while the adjoining compacted soil lost 1680 grams,--a
saving due to cultivation of nearly 60 per cent. Wagner, testing the
correctness of Nessler's work, found, in 1874, that cultivation
reduced the evaporation a little more than 60 per cent; Johnson, in
1878, confirmed the truth of the principle on American soils, and
Levi Stockbridge, working about the same time, also on American
soils, found that cultivation diminished evaporation on a clay soil
about 23 per cent, on a sandy loam 55 per cent, and on a heavy loam
nearly 13 per cent. All the early work done on this subject was done
under humid conditions, and it is only in recent years that
confirmation of this important principle has been obtained for the
soils of the dry-farm region. Fortier, working under California
conditions, determined that cultivation reduced the evaporation from
the soil surface over 55 per cent. At the Utah Station similar
experiments have shown that the saving of soil-moisture by
cultivation was 63 per cent for a clay soil, 34 per cent for a
coarse sand, and 13 per cent for a clay loam. Further, practical
experience has demonstrated time and time again that in cultivation
the dry-farmer has a powerful means of preventing evaporation from
agricultural soils.
Closely connected with cultivation is the practice of scattering
straw or other litter over the ground. Such artificial mulches are
very effective in reducing evaporation. Ebermayer found that by
spreading straw on the land, the evaporation was reduced 22 per
cent; Wagner found under similar conditions a saving of 38 per cent,
and these results have been confirmed by many other investigators.
On the modern dry-farms, which are large in area, the artificial
mulching of soils cannot become a very extensive practice, yet it is
well to bear the principle in mind. The practice of harvesting
dry-farm grain with the header and plowing under the high stubble in
the fall is a phase of cultivation for water conservation that
deserves special notice. The straw, thus incorporated into the soil,
decomposes quite readily in spite of the popular notion to the
contrary, and makes the soil more porous, and, therefore, more
effectively worked for the prevention of evaporation. When this
practice is continued for considerable periods, the topsoil becomes
rich in organic matter, which assists in retarding evaporation,
besides increasing the fertility of the land. When straw cannot be
fed to advantage, as is yet the case on many of the western
dry-farms, it would be better to scatter it over the land than to
burn it, as is often done. Anything that covers the ground or
loosens the topsoil prevents in a measure the evaporation of the
water stored in lower soil depths for the use of crops.
Depth of cultivation
The all-important practice for the dry-farmer who is entering upon
the growing season is cultivation. The soil must be covered
continually with a deep layer of dry loose soil, which because of
its looseness and dryness makes evaporation difficult. A leading
question in connection with cultivation is the depth to which the
soil should be stirred for the best results. Many of the early
students of the subject found that a soil mulch only one half inch
in depth was effective in retaining a large part of the
soil-moisture which noncultivated soils would lose by evaporation.
Soils differ greatly in the rate of evaporation from their surfaces.
Some form a natural mulch when dried, which prevents further water
loss. Others form only a thin hard crust, below which lies an active
evaporating surface of wet soil. Soils which dry out readily and
crumble on top into a natural mulch should be cultivated deeply, for
a shallow cultivation does not extend beyond the naturally formed
mulch. In fact, on certain calcareous soils, the surfaces of which
dry out quickly and form a good protection against evaporation,
shallow cultivations often cause a greater evaporation by disturbing
the almost perfect natural mulch. Clay or sand soils, which do not
so well form a natural mulch, will respond much better to shallow
cultivations. In general, however, the deeper the cultivation, the
more effective it is in reducing evaporation. Fortier, in the
experiments in California to which allusion has already been made,
showed the greater value of deep cultivation. During a period of
fifteen days, beginning immediately after an irrigation, the soil
which had not been mulched lost by evaporation nearly one fourth of
the total amount of water that had been added. A mulch 4 inches deep
saved about 72 per cent of the evaporation; a mulch 8 inches deep
saved about 88 per cent, and a mulch 10 inches deep stopped
evaporation almost wholly. It is a most serious mistake for the
dry-farmer, who attempts cultivation for soil-moisture conservation,
to fail to get the best results simply to save a few cents per acre
in added labor.
When to cultivate or till
It has already been shown that the rate of evaporation is greater
from a wet than from a dry surface. It follows, therefore, that the
critical time for preventing evaporation is when the soil is
wettest. After the soil is tolerably dry, a very large portion of
the soil-moisture has been lost, which possibly might have been
saved by earlier cultivation. The truth of this statement is well
shown by experiments conducted by the Utah Station. In one case on a
soil well filled with water, during a three weeks' period, nearly
one half of the total loss occurred the first, while only one fifth
fell on the third week. Of the amount lost during the first week,
over 60 per cent occurred during the first three days. Cultivation
should, therefore, be practiced as soon as possible after conditions
favorable for evaporation have been established. This means, first,
that in early spring, just as soon as the land is dry enough to be
worked without causing puddling, the soil should be deeply and
thoroughly stirred. Spring plowing, done as early as possible, is an
excellent practice for forming a mulch against evaporation. Even
when the land has been fall-plowed, spring plowing is very
beneficial, though on fall-plowed land the disk harrow is usually
used in early spring, and if it is set at rather a sharp angle, and
properly weighted, so that it cuts deeply into the ground, it is
practically as effective as spring plowing. The chief danger to the
dry-farmer is that he will permit the early spring days to slip by
until, when at last he begins spring cultivation, a large portion of
the stored soil-water has been evaporated. It may be said that deep
fall plowing, by permitting the moisture to sink quickly into the
lower layers of soil, makes it possible to get upon the ground
earlier in the spring. In fact, unplowed land cannot be cultivated
as early as that which has gone through the winter in a plowed
condition
If the land carries a fall-sown crop, early spring cultivation is
doubly important. As soon as the plants are well up in spring the
land should be gone over thoroughly several times if necessary, with
an iron tooth harrow, the teeth of which are set to slant backward
in order not to tear up the plants. The loose earth mulch thus
formed is very effective in conserving moisture; and the few plants
torn up are more than paid for by the increased water supply for the
remaining plants. The wise dry-fanner cultivates his land, whether
fallow or cropped, as early as possible in the spring.
Following the first spring plowing, disking, or cultivation, must
come more cultivation. Soon after the spring plowing, the land
should be disked and. then harrowed. Every device should be used to
secure the formation of a layer of loose drying soil over the land
surface. The season's crop will depend largely upon the
effectiveness of this spring treatment.
As the season advances, three causes combine to permit the
evaporation of soil-moisture.
First, there is a natural tendency, under the somewhat moist
conditions of spring, for the soil to settle compactly and thus to
restore the numerous capillary connections with the lower soil
layers through which water escapes. Careful watch should therefore
be kept upon the soil surface, and whenever the mulch is not loose,
the disk or harrow should be run over the land.
Secondly, every rain of spring or summer tends to establish
connections with the store of moisture in the soil. In fact, late
spring and summer rains are often a disadvantage on dry-farms, which
by cultural treatment have been made to contain a large store of
moisture. It has been shown repeatedly that light rains draw
moisture very quickly from soil layers many feet below the surface.
The rainless summer is not feared by the dry-farmer whose soils are
fertile and rich in moisture. It is imperative that at the very
earliest moment after a spring or summer rain the topsoil be well
stirred to prevent evaporation. It thus happens that in sections of
frequent summer rains, as in the Great Plains area, the farmer has
to harrow his land many times in succession, but the increased crop
yields invariably justify the added expenditure of effort.
Thirdly, on the summer-fallowed ground weeds start vigorously in the
spring and draw upon the soil-moisture, if allowed to grow, fully as
heavily as a crop of wheat or corn. The dry-farmer must not allow a
weed upon his land. Cultivation must he so continuous as to make
weeds an impossibility. The belief that the elements added to the
soil by weeds offset the loss of soil-moisture is wholly erroneous.
The growth of weeds on a fallow dry-farm is more dangerous than the
packed uncared-for topsoil. Many implements have been devised for
the easy killing of weeds, but none appear to be better than the
plow and the disk which are found on every farm. (See Chapter XV.)
When crops are growing on the land, thorough summer cultivation is
somewhat more difficult, but must be practiced for the greatest
certainty of crop yields. Potatoes, corn, and similar crops may be
cultivated with comparative ease, by the use of ordinary
cultivators. With wheat and the other small grains, generally, the
damage done to the crop by harrowing late in the season is too
great, and reliance is therefore placed on the shading power of the
plants to prevent undue evaporation. However, until the wheat and
other grains are ten to twelve inches high, it is perfectly safe to
harrow them. The teeth should be set backward to diminish the
tearing up of the plants, and the implement weighted enough to break
the soil crust thoroughly. This practice has been fully tried out
over the larger part of the dry-farm territory and found
satisfactory.
So vitally important is a permanent soil mulch for the conservation
for plant use of the water stored in the soil that many attempts
have been made to devise means for the effective cultivation of land
on which small grains and grasses are growing. In many places plants
have been grown in rows so far apart that a man with a hoe could
pass between them. Scofield has described this method as practiced
successfully in Tunis. Campbell and others in America have proposed
that a drill hole be closed every three feet to form a path wide
enough for a horse to travel in and to pull a large spring tooth
cultivator' with teeth so spaced as to strike between the rows of
wheat. It is yet doubtful whether, under average conditions, such
careful cultivation, at least of grain crops, is justified by the
returns. Under conditions of high aridity, or where the store of
soil-moisture is low, such treatment frequently stands between crop
success and failure, and it is not unlikely that methods will be
devised which will permit of the cheap and rapid cultivation between
the rows of growing wheat. Meanwhile, the dry-farmer must always
remember that the margin under which he works is small, and that his
success depends upon the degree to which he prevents small wastes.
Dry-farm potatoes, Rosebud Co., Montana, 1909. Yield, 282 bushels
per acre.
The conservation of soil-moisture depends upon the vigorous,
unremitting, continuous stirring of the topsoil. Cultivation!
cultivation! and more cultivation! must be the war-cry of the
dry-farmer who battles against the water thieves of an arid climate.
CHAPTER IX
REGULATING THE TRANSPIRATION
Water that has entered the soil may be lost in three ways. First, it
may escape by downward seepage, whereby it passes beyond the reach
of plant roots and often reaches the standing water. In dry-farm
districts such loss is a rare occurrence, for the natural
precipitation is not sufficiently large to connect with the country
drainage, and it may, therefore, be eliminated from consideration.
Second, soil-water may be lost by direct evaporation from the
surface soil. The conditions prevailing in arid districts favor
strongly this manner of loss of soil-moisture. It has been shown,
however, in the preceding chapter that the farmer, by proper and
persistent cultivation of the topsoil, has it in his power to reduce
this loss enough to be almost negligible in the farmer's
consideration. Third, soil-water may be lost by evaporation from the
plants themselves. While it is not generally understood, this source
of loss is, in districts where dry-farming is properly carried on,
very much larger than that resulting either from seepage or from
direct evaporation. While plants are growing, evaporation from
plants, ordinarily called transpiration, continues. Experiments
performed in various arid districts have shown that one and a half
to three times more water evaporates from the plant than directly
from well-tilled soil. To the present very little has been learned
concerning the most effective methods of checking or controlling
this continual loss of water. Transpiration, or the evaporation of
water from the plants themselves and the means of controlling this
loss, are subjects of the deepest importance to the dry-farmer.
Absorption
To understand the methods for reducing transpiration, as proposed in
this chapter, it is necessary to review briefly the manner in which
plants take water from the soil. The roots are the organs of water
absorption. Practically no water is taken into the plants by the
stems or leaves, even under conditions of heavy rainfall. Such small
quantities as may enter the plant through the stems and leaves are
of very little value in furthering the life and growth of the plant.
The roots alone are of real consequence in water absorption. All
parts of the roots do not possess equal power of taking up
soil-water. In the process of water absorption the younger roots are
most active and effective. Even of the young roots, however, only
certain parts are actively engaged in water absorption. At the very
tips of the young growing roots are numerous fine hairs. These
root-hairs, which cluster about the growing point of the young
roots, are the organs of the plant that absorb soil-water. They are
of value only for limited periods of time, for as they grow older,
they lose their power of water absorption. In fact, they are active
only when they are in actual process of growth. It follows,
therefore, that water absorption occurs near the tips of the growing
roots, and whenever a plant ceases to grow the water absorption
ceases also. The root-hairs are filled with a dilute solution of
various substances, as yet poorly understood, which plays an
important tent part in the ab sorption of water and plant-food from
the soil.
Owing to their minuteness, the root-hairs are in most cases immersed
in the water film that surrounds the soil particles, and the
soil-water is taken directly into the roots from the soil-water film
by the process known as osmosis. The explanation of this inward
movement is complicated and need not be discussed here. It is
sufficient to say that the concentration or strength of the solution
within the root-hair is of different degree from the soil-water
solution. The water tends, therefore, to move from the soil into the
root, in order to make the solutions inside and outside of the root
of the same concentration. If it should ever occur that the
soil-water and the water within the root-hair became the same
concentration, that is to say, contained the same substances in the
same proportional amounts, there would be no further inward movement
of water. Moreover, if it should happen that the soil-water is
stronger than the water within the root-hair, the water would tend
to pass from the plant into the soil. This is the condition that
prevails in many alkali lands of the West, and is the cause of the
death of plants growing on such lands.
It is clear that under these circumstances not only water enters the
root-hairs, but many of the substances found in solution in the
soil-water enter the plant also. Among these are the mineral
substances which are indispensable for the proper life and growth of
plants. These plant nutrients are so indispensable that if any one
of them is absent, it is absolutely impossible for the plant to
continue its life functions. The indispensable plant-foods gathered
from the soil by the root-hairs, in addition to water, are:
potassium, calcium, magnesium, iron, nitrogen, and phosphorus,--all
in their proper combinations. How the plant uses these substances is
yet poorly understood, but we are fairly certain that each one has
some particular function in the life of the plant. For instance,
nitrogen and phosphorus are probably necessary in the formation of
the protein or the flesh-forming portions of the plant, while potash
is especially valuable in the formation of starch.
There is a constant movement of the indispensable plant nutrients
after they have entered the root-hairs, through the stems and into
the leaves. This constant movement of the plant-foods depends upon
the fact that the plant consumes in its growth considerable
quantities of these substances, and as the plant juices are
diminished in their content of particular plant-foods, more enters
from the soil solution. The necessary plant-foods do not alone enter
the plant but whatever may be in solution in the soil-water enters
the plant in variable quantities. Nevertheless, since the plant uses
only a few definite substances and leaves the unnecessary ones in
solution, there is soon a cessation of the inward movement of the
unimportant constituents of the soil solution. This process is often
spoken of as selective absorption; that is, the plant, because of
its vital activity, appears to have the power of selecting from the
soil certain substances and rejecting others.
Movement of water through plant
The soil-water, holding in solution a great variety of plant
nutrients, passes from the root-hairs into the adjoining cells and
gradually moves from cell to cell throughout the whole plant. In
many plants this stream of water does not simply pass from cell to
cell, but moves through tubes that apparently have been formed for
the specific purpose of aiding the movement of water through the
plant. The rapidity of this current is often considerable.
Ordinarily, it varies from one foot to six feet per hour, though
observations are on record showing that the movement often reaches
the rate of eighteen feet per hour. It is evident, then, that in an
actively growing plant it does not take long for the water which is
in the soil to find its way to the uppermost parts of the plant.
The work of leaves
Whether water passes upward from cell to cell or through especially
provided tubes, it reaches at last the leaves, where evaporation
takes place. It is necessary to consider in greater detail what
takes place in leaves in order that we may more clearly understand
the loss due to transpiration. One half or more of every plant is
made up of the element carbon. The remainder of the plant consists
of the mineral substances taken from the soil (not more than two to
10 per cent of the dry plant) and water which has been combined with
the carbon and these mineral substances to form the characteristic
products of plant life. The carbon which forms over half of the
plant substance is gathered from the air by the leaves and it is
evident that the leaves are very active agents of plant growth. The
atmosphere consists chiefly of the gases oxygen and nitrogen in the
proportion of one to four, but associated with them are small
quantities of various other substances. Chief among the secondary
constituents of the atmosphere is the gas carbon dioxid, which is
formed when carbon burns, that is, when carbon unites with the
oxygen of the air. Whenever coal or wood or any carbonaceous
substance burns, carbon dioxid is formed. Leaves have the power of
absorbing the gas carbon dioxid from the air and separating the
carbon from the oxygen. The oxygen is returned to the atmosphere
while the carbon is retained to be used as the fundamental substance
in the construction by the plant of oils, fats, starches, sugars,
protein, and all the other products of plant growth.
This important process known as carbon assimilation is made possible
by the aid of countless small openings which exist chicfly on the
surfaces of leaves and known as "stomata." The stomata are
delicately balanced valves, exceedingly sensitive to external
influences. They are more numerous on the lower side than on the
upper side of plants. In fact, there is often five times more on the
under side than on the upper side of a leaf. It has been estimated
that 150,000 stomata or more are often found per square inch on the
under side of the leaves of ordinary cultivated plants. The stomata
or breathing-pores are so constructed that they may open and close
very readily. In wilted leaves they are practically closed; often
they also close immediately after a rain; but in strong sunlight
they are usually wide open. It is through the stomata that the gases
of the air enter the plant through which the discarded oxygen
returns to the atmosphere.
It is also through the stomata that the water which is drawn from
the soil by the roots through the stems is evaporated into the air.
There is some evaporation of water from the stems and branches of
plants, but it is seldom more than a thirtieth or a fortieth of the
total transpiration. The evaporation of water from the leaves
through the breathing-pores is the so-called transpiration, which is
the greatest cause of the loss of soil-water under dry-farm
conditions. It is to the prevention of this transpiration that much
investigation must be given by future students of dry-farming.
Transpiration
As water evaporates through the breathing-pores from the leaves it
necessarily follows that a demand is made upon the lower portions of
the plant for more water. The effect of the loss of water is felt
throughout the whole plant and is, undoubtedly, one of the chief
causes of the absorption of water from the soil. As evaporation is
diminished the amount of water that enters the plants is also
diminished. Yet transpiration appears to be a process wholly
necessary for plant life. The question is, simply, to what extent it
may be diminished without injuring plant growth. Many students
believe that the carbon assimilation of the plant, which is
fundamentally important in plant growth, cannot be continued unless
there is a steady stream of water passing through the plant and then
evaporating from the leaves.
Of one thing we are fairly sure: if the upward stream of water is
wholly stopped for even a few hours, the plant is likely to be so
severely injured as to be greatly handicapped in its future growth.
Botanical authorities agree that transpiration is of value to plant
growth, first, because it helps to distribute the mineral nutrients
necessary for plant growth uniformly throughout the plant; secondly,
because it permits an active assimilation of the carbon by the
leaves; thirdly, because it is not unlikely that the heat required
to evaporate water, in large part taken from the plant itself,
prevents the plant from being overheated. This last mentioned value
of transpiration is especially important in dry-farm districts,
where, during the summer, the heat is often intense. Fourthly,
transpiration apparently influences plant growth and development in
a number of ways not yet clearly understood.
Conditions influencing transpiration
In general, the conditions that determine the evaporation of water
from the leaves are the same as those that favor the direct
evaporation of water from soils, although there seems to be
something in the life process of the plant, a physiological factor,
which permits or prevents the ordinary water-dissipating factors
from exercising their full powers. That the evaporation of water
from the soil or from a free water surface is not the same as that
from plant leaves may be shown in a general way from the fact that
the amount of water transpired from a given area of leaf surface may
be very much larger or very much smaller than that evaporated from
an equal surface of free water exposed to the same conditions. It is
further shown by the fact that whereas evaporation from a free water
surface goes on with little or no interruption throughout the
twenty-four hours of the day, transpiration is virtually at a
standstill at night even though the conditions for the rapid
evaporation from a free water surface are present.
Some of the conditions influencing the transpiration may be
enumerated as follows:--
First, transpiration is influenced by the relative humidity. In dry
air, under otherwise similar conditions, plants transpire more water
than in moist air though it is to be noted that even when the
atmosphere is fully saturated, so that no water evaporates from a
free water surface, the transpiration of plants still continues in a
small degree. This is explained by the observation that since the
life process of a plant produces a certain amount of heat, the plant
is always warmer than the surrounding air and that transpiration
into an atmosphere fully charged with water vapor is consequently
made possible. The fact that transpiration is greater under a low
relative humidity is of greatest importance to the dry-farmer who
has to contend with the dry atmosphere.
Second, transpiration increases with the increase in temperature;
that is, under conditions otherwise the same, transpiration is more
rapid on a warm day than on a cold one. The temperature increase of
itself, however, is not sufficient to cause transpiration.
Third, transpiration increases with the increase of air currents,
which is to say, that on a windy day transpiration is much more
rapid than on a quiet day.
Fourth, transpiration increases with the increase of direct
sunlight. It is an interesting observation that even with the same
relative humidity, temperature, and wind, transpiration is reduced
to a minimum during the night and increases manyfold during the day
when direct sunlight is available. This condition is again to be
noted by the dry-farmer, for the dry-farm districts are
characterized by an abundance of sunshine.
Fifth, transpiration is decreased by the presence in the soil-water
of large quantities of the substances which the plant needs for its
food material. This will be discussed more fully in the next
section.
Sixth, any mechanical vibration of the plant seems to have some
effect upon the transpiration. At times it is increased and at times
it is decreased by such mechanical disturbance.
Seventh, transpiration varies also with the age of the plant. In the
young plant it is comparatively small. Just before blooming it is
very much larger and in time of bloom it is the largest in the
history of the plant. As the plant grows older transpiration
diminishes, and finally at the ripening stage it almost ceases.
Eighth, transpiration varies greatly with the crop. Not all plants
take water from the soil at the same rate. Very little is as yet
known about the relative water requirements of crops on the basis of
transpiration. As an illustration, MacDougall has reported that
sagebrush uses about one fourth as much water as a tomato plant.
Even greater differences exist between other plants. This is one of
the interesting subjects yet to be investigated by those who are
engaged in the reclamation of dry-farm districts. Moreover, the same
crop grown under different conditions varies in its rate of
transpiration. For instance, plants grown for some time under arid
conditions greatly modify their rate of transpiration, as shown by
Spalding, who reports that a plant reared under humid conditions
gave off 3.7 times as much water as the same plant reared under arid
conditions. This very interesting observation tends to confirm the
view commonly held that plants grown under arid conditions will
gradually adapt themselves to the prevailing conditions, and in
spite of the greater water dissipating conditions will live with the
expenditure of less water than would be the case under humid
conditions. Further, Sorauer found, many years ago, that different
varieties of the same crop possess very different rates of
transpiration. This also is an interesting subject that should be
more fully investigated in the future.
Ninth, the vigor of growth of a crop appears to have a strong
influence on transpiration. It does not follow, however, that the
more vigorously a crop grows, the more rapidly does it transpire
water, for it is well known that the most luxuriant plant growth
occurs in the tropics, where the transpiration is exceedingly low.
It seems to be true that under the same conditions, plants that grow
most vigorously tend to use proportionately the smallest amount of
water.
Tenth, the root system--its depth and manner of growth--influences
the rate of transpiration. The more vigorous and extensive the root
system, the more rapidly can water be secured from the soil by the
plant.
The conditions above enumerated as influencing transpiration are
nearly all of a physical character, and it must not be forgotten
that they may all be annulled or changed by a physiological
regulation. It must be admitted that the subject of transpiration is
yet poorly understood, though it is one of the most important
subjects in its applications to plant production in localities where
water is scaree. It should also be noted that nearly all of the
above conditions influencing transpiration are beyond the control of
the farmer. The one that seems most readily controlled in ordinary
agricultural practice will be discussed in the following section.
Plant-food and transpiration
It has been observed repeatedly by students of transpiration that
the amount of water which actually evaporates from the leaves is
varied materially by the substances held in solution by the
soil-water. That is, transpiration depends upon the nature and
concentration of soil solution. This fact, though not commonly
applied even at the present time, has really been known for a very
long time. Woodward, in 1699, observed that the amount of water
transpired by a plant growing in rain water was 192.3 grams; in
spring water, 163.6 grams, and in water from the River Thames, 159.5
grams; that is, the amount of water transpired by the plant in the
comparatively pure rain water was nearly 20 per cent higher than
that used by the plant growing in the notoriously impure water of
the River Thames. Sachs, in 1859, carried on an elaborate series of
experiments on transpiration in which he showed that the addition of
potassium nitrate, ammonium sulphate or common salt to the solution
in which plants grew reduced the transpiration; in fact, the
reduction was large, varying from 10 to 75 per cent. This was
confirmed by a number of later workers, among them, for instance,
Buergerstein, who, in 1875, showed that whenever acids were added to
a soil or to water in which plants are growing, the transpiration is
increased greatly; but when alkalies of any kind are added,
transpiration decreases. This is of special interest in the
development of dry-farming, since dry-farm soils, as a rule, contain
more substances that may be classed as alkalies than do soils
maintained under humid conditions. Sour soils are very
characteristic of districts where the rainfall is abundant; the
vegetation growing on such soils transpires excessively and the
crops are consequently more subject to drouth.
The investigators of almost a generation ago also determined beyond
question that whenever a complete nutrient solution is presented to
plants, that is, a solution containing all the necessary plant-foods
in the proper proportions, the transpiration is reduced immensely.
It is not necessary that the plant-foods should be presented in a
water solution in order to effect this reduction in transpiration;
if they are added to the soil on which plants are growing, the same
effect will result. The addition of commercial fertilizers to the
soil will therefore diminish transpiration. It was further
discovered nearly half a century ago that similar plants growing on
different soils evaporate different amounts of water from their
leaves; this difference, undoubtedly, is due to the conditions in
the fertility of the soils, for the more fertile a soil is, the
richer will the soil-water be in the necessary plant-foods. The
principle that transpiration or the evaporation of water from the
plants depends on the nature and concentration of the soil solution
is of far-reaching importance in the development of a rational
practice of dry-farming.
Transpiration for a pound of dry matter
Is plant growth proportional to transpiration? Do plants that
evaporate much water grow more rapidly than those that evaporate
less? These questions arose very early in the period characterized
by an active study of transpiration. If varying the transpiration
varies the growth, there would be no special advantage in reducing
the transpiration. From an economic point of view the important
question is this: Does the plant when its rate of transpiration is
reduced still grow with the same vigor? If that be the case, then
every effort should be made by the farmer to control and to diminish
the rate of transpiration.
One of the very earliest experiments on transpiration, conducted by
Woodward in 1699, showed that it required less water to produce a
pound of dry matter if the soil solution were of the proper
concentration and contained the elements necessary for plant growth.
Little more was done to answer the above questions for over one
hundred and fifty years. Perhaps the question was not even asked
during this period, for scientific agriculture was just coming into
being in countries where the rainfall was abundant. However,
Tschaplowitz, in 1878, investigated the subject and found that the
increase in dry matter is greatest when the transpiration is the
smallest. Sorauer, in researches conducted from 1880 to 1882,
determined with almost absolute certainty that less water is
required to produce a pound of dry matter when the soil is
fertilized than when it is not fertilized. Moreover, he observed
that the enriching of the soil solution by the addition of
artificial fertilizers enabled the plant to produce dry matter with
less water. He further found that if a soil is properly tilled so as
to set free plant-food and in that way to enrich the soil solution
the water-cost of dry plant substance is decreased. Hellriegel, in
1883, confirmed this law and laid down the law that poor plant
nutrition increases the water-cost of every pound of dry matter
produced. It was about this time that the Rothamsted Experiment
Station reported that its experiments had shown that during periods
of drouth the well-tilled and well-fertilized fields yielded good
crops, while the unfertilized fields yielded poor crops or crop
failures--indicating thereby, since rainfall was the critical
factor, that the fertility of the soil is important in determining
whether or not with a small amount of water a good crop can be
produced. Pagnoul, working in 1895 with fescue grass, arrived at the
same conclusion. On a poor clay soil it required 1109 pounds of
water to produce one pound of dry matter, while on a rich calcareous
soil only 574 pounds were required. Gardner of the United States
Department of Agriculture, Bureau of Soils, working in 1908, on the
manuring of soils, came to the conclusion that the more fertile the
soil the less water is required to produce a pound of dry matter. He
incidentally called attention to the fact that in countries of
limited rainfall this might be a very important principle to apply
in crop production. Hopkins in his study of the soils of Illinois
has repeatedly observed, in connection with certain soils, that
where the land is kept fertile, injury from drouth is not common,
implying thereby that fertile soils will produce dry matter at a
lower water-cost. The most recent experiments on this subject,
conducted by the Utah Station, confirm these conclusions. The
experiments, which covered several years, were conducted in pots
filled with different soils. On a soil, naturally fertile, 908
pounds of water were transpired for each pound of dry matter (corn)
produced; by adding to this soil an ordinary dressing of manure'
this was reduced to 613 pounds, and by adding a small amount of
sodium nitrate it was reduced to 585 pounds. If so large a reduction
could be secured in practice, it would seem to justify the use of
commercial fertilizers in years when the dry-farm year opens with
little water stored in the soil. Similar results, as will be shown
below, were obtained by the use of various cultural methods. It may
therefore, be stated as a law, that any cultural treatment which
enables the soil-water to acquire larger quantities of plant-food
also enables the plant to produce dry matter with the use of a
smaller amount of water. In dry-farming, where the limiting factor
is water, this principle must he emphasized in every cultural
operation.
Methods of controlling transpiration
It would appear that at present the only means possessed by the
farmer for controlling transpiration and making possible maximum
crops with the minimum amount of water in a properly tilled soil is
to keep the soil as fertile as is possible. In the light of this
principle the practices already recommended for the storing of water
and for the prevention of the direct evaporation of water from the
soil are again emphasized. Deep and frequent plowing, preferably in
the fall so that the weathering of the winter may be felt deeply and
strongly, is of first importance in liberating plant-food.
Cultivation which has been recommended for the prevention of the
direct evaporation of water is of itself an effective factor in
setting free plant-food and thus in reducing the amount of water
required by plants. The experiments at the Utah Station, already
referred to, bring out very strikingly the value of cultivation in
reducing the transpiration. For instance, in a series of experiments
the following results were obtained. On a sandy loam, not
cultivated, 603 pounds of water were transpired to produce one pound
of dry matter of corn; on the same soil, cultivated, only 252 pounds
were required. On a clay loam, not cultivated, 535 pounds of water
were transpired for each pound of dry matter, whereas on the
cultivated soil only 428 pounds were necessary. On a clay soil, not
cultivated, 753 pounds of water were transpired for each pound of
dry matter; on the cultivated soil, only 582 pounds. The farmer who
faithfully cultivates the soil throughout the summer and after every
rain has therefore the satisfaction of knowing that he is
accomplishing two very important things: he is keeping the moisture
in the soil, and he is making it possible for good crops to be grown
with much less water than would otherwise be required. Even in the
case of a peculiar soil on which ordinary cultivation did not reduce
the direct evaporation, the effect upon the transpiration was very
marked. On the soil which was not cultivated, 451 pounds of water
were required to produce one pound of dry matter (corn), while on
the cultivated soils, though the direct evaporation was no smaller,
the number of pounds of water for each pound of dry substance was as
low as 265.
One of the chief values of fallowing lies in the liberation of the
plant-food during the fallow year, which reduces the quantity of
water required the next year for the full growth of crops. The Utah
experiments to which reference has already been made show the effect
of the previous soil treatment upon the water requirements of crops.
One half of the three types of soil had been cropped for three
successive years, while the other half had been left bare. During
the fourth year both halves were planted to corn. For the sandy loam
it was found that, on the part that had been cropped previously, 659
pounds of water were required for each pound of dry matter produced,
while on the part that had been bare only 573 pounds were required.
For the clay loam 889 pounds on the cropped part and 550 on the
previously bare part were required for each pound of dry matter. For
the clay 7466 pounds on the cropped part and 1739 pounds on the
previously bare part were required for each pound of dry matter.
These results teach clearly and emphatically that the fertile
condition of the soil induced by fallowing makes it possible to
produce dry matter with a smaller amount of water than can be done
on soils that are cropped continuously. The beneficial effects of
fallowing are therefore clearly twofold: to store the moisture of
two seasons for the use of one crop; and to set free fertility to
enable the plant to grow with the least amount of water. It is not
yet fully understood what changes occur in fallowing to give the
soil the fertility which reduces the water needs of the plant. The
researches of Atkinson in Montana, Stewart and Graves in Utah, and
Jensen in South Dakota make it seem probable that the formation of
nitrates plays an important part in the whole process. If a soil is
of such a nature that neither careful, deep plowing at the right
time nor constant crust cultivation are sufficient to set free an
abundance of plant-food, it may be necessary to apply manures or
commercial fertilizers to the soil. While the question of restoring
soil fertility has not yet come to be a leading one in dry-farming,
yet in view of what has been said in this chapter it is not
impossible that the time will come when the farmers must give
primary attention to soil fertility in addition to the storing and
conservation of soil-moisture. The fertilizing of lands with proper
plant-foods, as shown in the last sections, tends to check
transpiration and makes possible the production of dry matter at the
lowest water-cost.
The recent practice in practically all dry-farm districts, at least
in the intermountain and far West, to use the header for harvesting
bears directly upon the subject considered in this chapter. The high
stubble which remains contains much valuable plant-food, often
gathered many feet below the surface by the plant roots. When this
stubble is plowed under there is a valuable addition of the
plant-food to the upper soil. Further, as the stubble decays, acid
substances are produced that act upon the soil grains to set free
the plant-food locked up in them. The plowing under of stubble is
therefore of great value to the dry-farmer. The plowing under of any
other organic substance has the same effect. In both cases fertility
is concentrated near the surface, which dissolves in the soil-water
and enables the crop to mature with the Ieast quantity of water.
The lesson then to be learned from this chapter is, that it is not
aufficient for the dry-farmer to store an abundance of water in the
soil and to prevent that water from evaporating directly from the
soil; but the soil must be kept in such a state of high fertility
that plants are enabled to utilize the stored moisture in the most
economical manner. Water storage, the prevention of evaporation, and
the maintenance of soil fertility go hand in hand in the development
of a successful system of farming without irrigation.
CHAPTER X
PLOWING AND FALLOWING
The soil treatment prescribed in the preceding chapters rests upon
(1) deep and thorough plowing, done preferably in the fall; (2)
thorough cultivation to form a mulch over the surface of the land,
and (3) clean summer fallowing every other year under low rainfall
or every third or fourth year under abundant rainfall.
Students of dry-farming all agree that thorough cultivation of the
topsoil prevents the evaporation of soil-moisture, but some have
questioned the value of deep and fall plowing and the occasional
clean summer fallow. It is the purpose of this chapter to state the
findings of practical men with reference to the value of plowing and
fallowing in producing large crop yields under dry-farm conditions.
It will be shown in Chapter XVIII that the first attempts to produce
crops without irrigation under a limited rainfall were made
independently in many diverse places. California, Utah, and the
Columbia Basin, as far as can now be learned, as well as the Great
Plains area, were all independent pioneers in the art of
dry-farming. It is a most significant fact that these diverse
localities, operating under different conditions as to soil and
climate, have developed practically the same system of dry-farming.
In all these places the best dry-farmers practice deep plowing
wherever the subsoil will permit it; fall plowing wherever the
climate will permit it; the sowing of fall grain wherever the
winters will permit it, and the clean summer fallow every other
year, or every third or fourth year. H. W. Campbell, who has been
the leading exponent of dry-farming in the Great Plains area, began
his work without the clean summer fallow as a part of his system,
but has long since adopted it for that section of the country. It is
scarcely to be believed that these practices, developed laboriously
through a long succession of years in widely separated localities,
do not rest upon correct scientific principles. In any case, the
accumulated experience of the dry-farmers in this country confirms
the doctrines of soil tillage for dry-farms laid down in the
preceding chapters.
At the Dry-Farming Congresses large numbers of practical farmers
assemble for the purpose of exchanging experiences and views. The
reports of the Congress show a great difference of opinion on minor
matters and a wonderful unanimity of opinion on the more fundamental
questions. For instance, deep plowing was recommended by all who
touched upon the subject in their remarks; though one farmer, who
lived in a locality the subsoil of which was very inert, recommended
that the depth of plowing should be increased gradually until the
full depth is reached, to avoid a succession of poor crop years
while the lifeless soil was being vivified. The states of Utah,
Montana, Wyoming, South Dakota, Colorado, Kansas, Nebraska, and the
provinces of Alberta and Saskatchewan of Canada all specifically
declared through one to eight representatives from each state in
favor of deep plowing as a fundamental practice in dry-farming. Fall
plowing, wherever the climatic conditions make it possible, was
similarly advocated by all the speakers. Farmers in certain
localities had found the soil so dry in the fall that plowing was
difficult, but Campbell insisted that even in such places it would
be profitable to use power enough to break up the land before the
winter season set in. Numerous speakers from the states of Utah,
Wyoming, Montana, Nebraska, and a number of the Great Plains states,
as well as from the Chinese Empire, declared themselves as favoring
fall plowing. Scareely a dissenting voice was raised.
In the discussion of the clean summer fallow as a vital principle of
dry-farming a slight difference of opinion was discovered. Farmers
from some of the localities insisted that the clean summer fallow
every other year was indispensable; others that one in three years
was sufficient; and others one in four years, and a few doubtful the
wisdom of it altogether. However, all the speakers agreed that clean
and thorough cultivation should be practiced faithfully during the
spring, and fall of the fallow year. The appreciation of the fact
that weeds consume precious moisture and fertility seemed to be
general among the dry-farmers from all sections of the country. The
following states, provinces, and countries declared themselves as
being definitely and emphatically in favor of clean summer
fallowing:
California, Utah, Nevada, Washington, Montana, Idaho, Colorado, New
Mexico, North Dakota, Nebraska, Alberta, Saskatchewan, Russia,
Turkey, the Transvaal, Brazil, and Australia. Each of these many
districts was represented by one to ten or more representatives. The
only state to declare somewhat vigorously against it was from the
Great Plains area, and a warning voice was heard from the United
States Department of Agriculture. The recorded practical experience
of the farmers over the whole of the dry-farm territory of the
United States leads to the conviction that fallowing must he
accepted as a practice which resulted in successful dry-farming.
Further, the experimental leaders in the dry-farm movement, whether
working under private, state, or governmental direction, are, with
very few exceptions, strongly in favor of deep fall plowing and
clean summer fallowing as parts of the dry-farm system.
The chief reluctance to accept clean summer fallowing as a principle
of dry-farming appears chicfly among students of the Great Plains
area. Even there it is admitted by all that a wheat crop following a
fallow year is larger and better than one following wheat. There
seem, however, to be two serious reasons for objecting to it. First,
a fear that a clean summer fallow, practiced every second, third, or
fourth year, will cause a large diminution of the organic matter in
the soil, resulting finally in complete crop failure; and second, a
belief that a hoed crop, like corn or potatoes, exerts the same
beneficial effect.
It is undoubtedly true that the thorough tillage involved in
dry-farming exposes to the action of the elements the organic matter
of the soil and thereby favors rapid oxidation. For that reason the
different ways in which organic matter may be supplied regularly to
dry-farms are pointed out in Chapter XIV. It may also be observed
that the header harvesting system employed over a large part of the
dry-farm territory leaves the large header stubble to be plowed
under, and it is probable that under such methods more organic
matter is added to the soil during the year of cropping than is lost
during the year of fallowing. It may, moreover, be observed that
thorough tillage of a crop like corn or potatoes tends to cause a
loss of the organic matter of the soil to a degree nearly as large
as is the case when a fallow field is well cultivated. The thorough
stirring of the soil under an arid or semiarid climate, which is an
essential feature of dry-farming, will always result in a decrease
in organic matter. It matters little whether the soil is fallow or
in crop during the process of cultivation, so far as the result is
concerned.
A serious matter connected with fallowing in the Great Plains area
is the blowing of the loose well-tilled soil of the fallow fields,
which results from the heavy winds that blow so steadily over a
large part of the western slope of the Mississippi Valley. This is
largely avoided when crops are grown on the land, even when it is
well tilled.
The theory, recently proposed, that in the Great Plains area, where
the rains come chicfly in summer, the growing of hoed crops may take
the place of the summer fallow, is said to be based on experimental
data not yet published. Careful and conscientious experimenters, as
Chilcott and his co-laborers, indicate in their statements that in
many cases the yields of wheat, after a hoed crop, have been larger
than after a fallow year. The doctrine has, therefore, been rather
widely disseminated that fallowing has no place in the dry-farming
of the Great Plains area and should be replaced by the growing of
hoed crops. Chilcott, who is the chief exponent of this doctrine,
declares, however, that it is only with spring-grown crops and for a
succession of normal years that fallowing may be omitted, and that
fallowing must be resorted to as a safeguard or temporary expedient
to guard against total loss of crop where extreme drouth is
anticipated; that is, where the rainfall falls below the average. He
further explains that continuous grain cropping, even with careful
plowing and spring and fall tillage, is unsuccessful; but holds that
certain rotations of crops, including grain and a hoed crop every
other year, are often more profitable than grain alternating with
clean summer fallow. He further believes that the fallow year every
third or fourth year is sufficient for Great Plains conditions.
Jardine explains that whenever fall grain is grown in the Great
Plains area, the fallow is remarkably helpful, and in fact because
of the dry winters is practically indispensable.
This latter view is confirmed by the experimental results obtained
by Atkinson and others at the Montana Experiment Stations, which are
conducted under approximately Great Plains conditions.
It should be mentioned also that in Saskatchewan, in the north end
of the Great Plains area, and which is characteristic, except for a
lower annual temperature, of the whole area, and where dry-farming
has been practiced for a quarter of a century, the clean summer
fallow has come to be an established practice.
This recent discussion of the place of fallowing in the agriculture
of the Great Plains area illustrates what has been said so often in
this volume about the adapting of principles to local conditions.
Wherever the summer rainfall is sufficient to mature a crop,
fallowing for the purpose of storing moisture in the soil is
unnecessary; the only value of the fallow year under such conditions
would be to set free fertility. In the Great Plains area the
rainfall is somewhat higher than elsewhere in the dry-farm territory
and most of it comes in summer; and the summer precipitation is
probably enough in average years to mature crops, providing soil
conditions are favorable. The main considerations, then, are to keep
the soils open for the reception of water and to maintain the soils
in a sufficiently fertile condition to produce, as explained in
Chapter IX, plants with a minimum amount of water. This is
accomplished very largely by the year of hoed crop, when the soil is
as well stirred as under a clean fallow.
The dry-farmer must never forget that the critical element in
dry-farming is water and that the annual rainfall will in the very
nature of things vary from year to year, with the result that the
dry year, or the year with a precipitation below the average, is
sure to come. In somewhat wet years the moisture stored in the soil
is of comparatively little consequence, but in a year of drouth it
will be the main dependence of the farmer. Now, whether a crop be
hoed or not, it requires water for its growth, and land which is
continuously cropped even with a variety of crops is likely to be so
largely depleted of its moisture that, when the year of drouth
comes, failure will probably result.
The precariousness of dry-farming must be done away with. The year
of drouth must be expected every year. Only as certainty of crop
yield is assured will dry-farming rise to a respected place by the
side of other branches of agriculture. To attain such certainty and
respect clean summer fallowing every second, third, or fourth year,
according to the average rainfall, is probably indispensable; and
future investigations, long enough continued, will doubtless confirm
this prediction. Undoubtedly, a rotation of crops, including hoed
crops, will find an important place in dry-farming, but probably not
to the complete exclusion of the clean summer fallow.
Jethro Tull, two hundred years ago, discovered that thorough tillage
of the soil gave crops that in some cases could not be produced by
the addition of manure, and he came to the erroneous conclusion that
"tillage is manure." In recent days we have learned the value of
tillage in conserving moisture and in enabling plants to reach
maturity with the least amount of water, and we may be tempted to
believe that "tillage is moisture." This, like Tull's statement, is
a fallacy and must be avoided. Tillage can take the place of
moisture only to a limited degree. Water is the essential
consideration in dry-farming, else there would be no dry-farming.
CHAPTER XI
SOWING AND HARVESTING
The careful application of the principles of soil treatment
discussed in the preceding chapters will leave the soil in good
condition for sowing, either in the fall or spring. Nevertheless,
though proper dry-farming insures a first-class seed-bed, the
problem of sowing is one of the most difficult in the successful
production of crops without irrigation. This is chiefly due to the
difficulty of choosing, under somewhat rainless conditions, a time
for sowing that will insure rapid and complete germination and the
establishmcnt of a root system capable of producing good plants. In
some respects fewer definite, reliable principles can be laid down
concerning sowing than any other principle of important application
in the practice of dry-farming. The experience of the last fifteen
years has taught that the occasional failures to which even good
dry-farmers have been subjected have been caused almost wholly by
uncontrollable unfavorable conditions prevailing at the time of
sowing.
Conditions of germination
Three conditions determine germination: (1) heat, (2) oxygen, and
(3) water. Unless these three conditions are all favorable, seeds
cannot germinate properly. The first requisite for successful seed
germination is a proper degree of heat. For every kind of seed there
is a temperature below which germination does not occur; another,
above which it does not occur, and another, the best, at which,
providing the other factors are favorable, germination will go on
most rapidly. The following table, constructed by Goodale, shows the
latest, highest, and best germination temperatures for wheat,
barley, and corn. Other seeds germinate approximately within the
same ranges of temperature:--
Germination Temperatures (Degrees Farenheit)
Lowest Highest Best
Wheat 41 108 84
Barley 41 100 84
Corn 49 115 91
Germination occurs within the considerable range between the highest
and lowest temperatures of this table, though the rapidity of
germination decreases as the temperature recedes from the best. This
explains the early spring and late fall germination when the
temperature is comparatively low. If the temperature falls below the
lowest required for germination, dry seeds are not injured, and even
a temperature far below the freezing point of water will not affect
seeds unfavorably if they are not too moist. The warmth of the soil,
essential to germination, cannot well be controlled by the farmer;
and planting must, therefore, be done in seasons when, from past
experience, it is probable that the temperature is and will remain
in the neighborhood of the best degree for germination. More heat is
required to raise the temperature of wet soils; therefore, seeds
will generally germinate more slowly in wet than in dry soils, as is
illustrated in the rapid germination often observed in well-tilled
dry-farm soils. Consequently, it is safer at a low temperature to
sow in dry soils than in wet ones. Dark soils absorb heat more
rapidly than lighter colored ones, and under the same conditions of
temperature germination is therefore more likely to go on rapidly in
dark colored soils. Over the dry-farm territory the soils are
generally light colored, which would tend to delay germination. The
incorporation of organic matter with the soil, which tends to darken
the soil, has a slight though important bearing on germination as
well as on the general fertility of the soil, and should be made an
important dry-farm practice. Meanwhile, the temperature of the soil
depends almost wholly upon the prevailing temperature conditions in
the district and is not to any material degree under the control of
the farmer.
A sufficient supply of oxygen in the soil is indispensable to
germination. Oxygen, as is well known, forms about one fifth of the
atmosphere and is the active principle in combustion and in tile
changes in the animal body occasioned by respiration. Oxygen should
be present in the soil air in approximately the proportion in which
it is found in the atmosphere. Germination is hindered by a larger
or smaller proportion than is found in the atmosphere. The soil must
be in such a condition that the air can easily enter or leave the
upper soil layer; that is, the soil must be somewhat loose. In order
that the seeds may have access to the necessary oxygen, then, sowing
should not be done in wet or packed soils, nor should the sowing
implements be such as to press the soil too closely around the
seeds. Well-fallowed soil is in an ideal condition for admitting
oxygen.
If the temperature is right, germination begins by the forcible
absorption of water by the seed from the surrounding soil. The force
of this absorption is very great, ranging from four hundred to five
hundred pounds per square inch, and continues until the seed is
completely saturated. The great vigor with which water is thus
absorbed from the soil explains how seeds are able to secure the
necessary water from the thin water film surrounding the soil
grains. The following table, based upon numerous investigations
conducted in Germany and in Utah, shows the maximum percentages of
water contained by seeds when the absorption is complete. These
quantities are reached only when water is easily accessible:--
Percentage of Water contained by Seeds at Saturation
German Utah
Rye 58 --
Wheat 57 52
Oats 58 43
Barley 56 44
Corn 44 57
Beans 95 88
Lucern 78 67
Germination itself does not go on freely until this maximum
saturation has been reached. Therefore, if the moisture in the soil
is low, the absorption of water is made difficult and germination is
retarded. This shows itself in a decreased percentage of
germination. The effect upon germination of the percentage of water
in the soil is well shown by some of the Utah experiments, as
follows:--
Effect of Varying Amounts of Water on Percentage of Germination
Percent water in soil 7.5 10 12.5 15 17.5 20 22.5 25
Wheat in sandy loam 0.0 98 94 86 82 82 82 6
Wheat in clay 30 48 84 94 84 82 86 58
Beans in sandy loam 0 0 20 46 66 18 8 9
Beans in clay 0 0 6 20 22 32 30 36
Lucern in Sandy loam 0 18 68 54 54 8 8 9
Lucern in clay 8 8 54 48 50 32 15 14
In a sandy soil a small percentage of water will cause better
germination than in a clay soil. While different seeds vary in their
power to abstract water from soils, yet it seems that for the
majority of plants, the best percentage of soil-water for
germination purposes is that which is in the neighborhood of the
maximum field capacity of soils for water, as explained in Chapter
VII. Bogdanoff has estimated that the best amount of water in the
soil for germination purposes is about twice the maximum percentage
of hygroscopic water. This would not be far from the field-water
capacity as described in the preceding chapter.
During the absorption of water, seeds swell considerably, in many
cases from two to three times their normal size. This has the very
desirable effect of crowding the seed walls against the soil
particles and thus, by establishing more points of contact, enabling
the seed to absorb moisture with greater facility. As seeds begin to
absorb water, heat is also produced. In many cases the temperature
surrounding the seeds is increased one degree on the Centigrade
scale by the mere process of water absorption. This favors rapid
germination. Moreover, the fertility of the soil has a direct
influence upon germination. In fertile soils the germination is more
rapid and more complete than in infertile soils. Especially active
in favoring direct germination are the nitrates. When it is recalled
that the constant cultivation and well-kept summer fallow of
dry-farming develop large quantities of nitrates in the soil, it
will be understood that the methods of dry-farming as already
outlined accelerate germination very greatly.
It scareely need be said that the soil of the seed-bed should be
fine, mellow, and uniform in physical texture so that the seeds can
be planted evenly and in close contact with the soil particles. All
the requisite conditions for germination are best met by the
conditions prevailing in a well-kept summer fallowed soil.
Time to sow
In the consideration of the time to sow, the first question to be
disposed of by the dry-farmer is that of fall as against spring
sowing. The small grains occur as fall and spring varieties, and it
is vitally important to determine which season, under dry-farm
conditions, is the best for sowing.
The advantages of fall sowing are many. As stated, successful
germination is favored by the presence of an abundance of fertility,
especially of nitrates, in the soil. In summer-fallowed land
nitrates are always found in abundance in the fall, ready to
stimulate the seed into rapid germination and the young plants into
vigorous growth. During the late fall and winter months the nitrates
disappear, at least in part, anti from the point of view of
fertility the spring is not so desirable as the fall for
germination. More important, grain sown in the fall under favorable
conditions will establish a good root system which is ready for use
and in action in the early spring as soon as the temperature is
right and long before the farmer can go out on the ground with his
implements. As a result, the crop has the use of the early spring
moisture, which under the conditions of spring sowing is evaporated
into the air. Where the natural precipitation is light and the
amount of water stored in the soil is not large, the gain resulting
from the use of the early spring moisture. often decides the
question in favor of fall sowing.
The disadvantages of fall sowing are also many. The uncertainty of
the fall rains must first be considered. In ordinary practice, seed
sown in the fall does not germinate until a rain comes, unless
indeed sowing is done immediately after a rain. The fall rains are
uncertain as to quantity. In many cases they are so light that they
suffice only to start germination and not to complete it and give
the plants the proper start. Such incomplete germination frequently
causes the total loss of the crop. Even if the stand of the fall
crop is satisfactory, there is always the danger of winter-killing
to be reckoned with. The real cause of winter-killing is not yet
clearly understood, though it seems that repeated thawing and
freezing, drying winter winds, accompanied by dry cold or protracted
periods of intense cold, destroy the vitality of the seed and young
root system. Continuous but moderate cold is not ordinarily very
injurious. The liability to winter-killing is, therefore, very much
greater wherever the winters are open than in places where the snow
covers the ground the larger part of the winter. It is also to be
kept in mind that some varieties are very resistant to
winter-killing, while others require well-covered winters. Fall
sowing is preferable wherever the bulk of the precipitation comes in
winter and spring and where the winters are covered for some time
with snow and the summers are dry. Under such conditions it is very
important that the crop make use of the moisture stored in the soil
in the early spring. Wherever the precipitation comes largely in
late spring and summer, the arguments in favor of fall sowing are
not so strong, and in such localities spring sowing is often more
desirable than fall sowing. In the Great Plains district, therefore,
spring sowing is usually recommended, though fall-sown crops nearly
always, even there, yield the larger crops. In the intermountain
states, with wet winters and dry summers, fall sowing has almost
wholly replaced spring sowing. In fact, Farrell reports that upon
the Nephi (Utah) substation the average of six years shows about
twenty bushels of wheat from fall-sown seed as against about
thirteen bushels from spring-sown seed. Under the California
climate, with wet winters and a winter temperature high enough for
plant growth, fall sowing is also a general practice. Wherever the
conditions are favorable, fall sowing should be practiced, for it is
in harmony with the best principles of water conservation. Even in
districts where the precipitation comes chiefly in the summer, it
may be found that fall sowing, after all, is preferable.
The right time to sow in the fall can be fixed only with great
difficulty, for so much depends upon the climatic conditions. In
fact the practice varies in accordance with differences in fall
precipitation and early fall frosts. Where numerous fall rains
maintain the soil in a fairly moist condition and the temperature is
not too low, the problem is comparatively simple. In such districts,
for latitudes represented by the dry-farm sections of the United
States, a good time for fall planting is ordinarily from the first
of September to the middle of October. If sown much earlier in such
districts, the growth is likely to be too rank and subject to
dangerous injury by frosts, and as suggested by Farrell the very
large development of the root system in the fall may cause, the
following summer, a dangerously large growth of foliage; that is,
the crop may run to straw at the expense of the grain. If sown much
later, the chances are that the crop will not possess sufficient
vitality to withstand the cold of late fall and winter. In
localities where the late summer and the early fall are rainless, it
is much more difficult to lay down a definite rule covering the time
of fall sowing. The dry-farmers in such places usually sow at any
convenient time in the hope that an early rain will start the
process of germination and growth. In other cases planting is
delayed until the arrival of the first fall rain. This is an certain
and usually unsatisfactory practice, since it often happens that the
sowing is delayed until too late in the fall for the best results.
In districts of dry late summer and fall, the greatest danger in
depending upon the fall rains for germination lies in the fact that
the precipitation is often so small that it initiates germination
without being sufficient to complete it. This means that when the
seed is well started in germination, the moisture gives out. When
another slight rain comes a little later, germination is again
started and possibly again stopped. In some seasons this may occur
several times, to the permanent injury of the crop. Dry-farmers try
to provide against this danger by using an unusually large amount of
seed, assuming that a certain amount will fail to come up because of
the repeated partial germinations. A number of investigators have
demonstrated that a seed may start to germinate, then be dried, and
again be started to germinate several times in succession without
wholly destroying the vitality of the seed.
In these experiments wheat and other seeds were allowed to germinate
and dry seven times in succession. With each partial germination the
percentage of total germination decreased until at the seventh
germination only a few seeds of wheat, barley, and oats retained
their power. This, however, is practically the condition in dry-farm
districts with rainless summers and falls, where fall seeding is
practiced. In such localities little dependence should be placed on
the fall rains and greater reliance placed on a method of soil
treatment that will insure good germination. For this purpose the
summer fallow has been demonstrated to be the most desirable
practice. If the soil has been treated according to the principles
laid down in earlier chapters, the fallowed land will, in the fall,
contain a sufficient amount of moisture to produce complete
germination though no rains may fall. Under such conditions the main
consideration is to plant the seed so deep that it may draw freely
upon the stored soil-moisture. This method makes fall germination
sure in districts where the natural precipitation is not to be
depended upon.
When sowing is done in the spring, there are few factors to
consider. Whenever the temperature is right and the soil has dried
out sufficiently so that agricultural implements may be used
properly, it is usually safe to begin sowing. The customs which
prevail generally with regard to the time of spring sowing may be
adopted in dry-farm practices also.
Depth of seeding
The depth to which seed should be planted in the soil is of
importance in a system of dry-farming. The reserve materials in
seeds are used to produce the first roots and the young plants. No
new nutriment beyond that stored in the soil can be obtained by the
plant until the leaves are above the ground able to gather Carleton
from the atmosphere. The danger of deep planting lies, therefore, in
exhausting the reserve materials of the seeds before the plant has
been able to push its leaves above the ground. Should this occur,
the plant will probably die in the soil. On the other hand, if the
seed is not planted deeply enough, it may happen that the roots
cannot be sent down far enough to connect with the soil-water
reservoir below. Then, the root system will not be strong and deep,
but will have to depend for its development upon the surface water,
which is always a dangerous practice in dry-farming. The rule as to
the depth of seeding is simply: Plant as deeply as is safe. The
depth to which seeds may be safely placed depends upon the nature of
the soil, its fertility, its physical condition, and the water that
it contains. In sandy soils, planting may be deeper than in clay
soils, for it requires less energy for a plant to push roots, stems,
and leaves through the loose sandy soil than through the more
compact clay soil; in a dry soil planting may be deeper than in wet
soils; likewise, deep planting is safer in a loose soil than in one
firmly compacted; finally, where the moist soil is considerable
distance below the surface, deeper planting may be practiced than
when the moist soil is near the surface. Countless experiments have
been conducted on the subject of depth of seeding. In a few cases,
ordinary agricultural seeds planted eight inches deep have come up
and produced satisfactory plants. However, the consensus of opinion
is that from one to three inches are best in humid districts, but
that, everything considered, four inches is the best depth under
dry-farm conditions. Under a low natural precipitation, where the
methods of dry-farming are practiced, it is always safe to plant
deeply, for such a practice will develop and strengthen the root
system, which is one big step toward successful dry-farming.
Quantity to sow
Numerous dry-farm failures may be charged wholly to ignorance
concerning the quantity of seed to sow. In no other practice has the
custom of humid countries been followed more religiously by
dry-farmers, and failure has nearly always resulted. The discussions
in this volume have brought out the fact that every plant of
whatever character requires a large amount of water for its growth.
From the first day of its growth to the day of its maturity, large
amounts of water are taken from the soil through the plant and
evaporated into the air through the leaves. When the large
quantities of seed employed in humid countries have been sown on dry
lands, the result has usually been an excellent stand early in the
season, with a crop splendid in appearance up to early summer. .A
luxuriant spring crop reduces, however, the water content of the
soil so greatly that when the heat of the summer arrives, there is
not sufficient water left in the soil to support the final
development and ripening. A thick stand in early spring is no
assurance to the dry-farmer of a good harvest. On the contrary, it
is usually the field with a thin stand in spring that stands up best
through the summer and yields most at the time of harvest. The
quantity of seed sown should vary with the soil conditions: the more
fertile the soil is, the more seed may be used; the more water in
the soil, the more seed may be sown; as the fertility or the water
content diminishes, the amount of seed should likewise be
diminished. Under dry-farm conditions the fertility is good, but the
moisture is low. As a general principle, therefore, light seeding
should be practiced on dry-farms, though it should be sufficient to
yield a crop that will shade the ground well. If the sowing is done
early, in fall or spring, less seed may be used than if the sowing
is late, because the early sowing gives a better chance for root
development, which results, ordinarily, in more vigorous plants that
consume more moisture than the smaller and weaker plants of later
sowing. If the winters are mild and well covered with snow, less
seed may be used than in districts where severe or open winters
cause a certain amount of winter-killing. On a good seed-bed of
fallowed soil less seed may be used than where the soil has not been
carefully tilled and is somewhat rough and lumpy and unfavorable for
complete germination. The yield of any crop is not directly
proportional to the amount sown, unless all factors contributing to
germination are alike. In the case of wheat and other grains, thin
seeding also gives a plant a better chance for stooling, which is
Nature's method of adapting the plant to the prevailing moisture and
fertility conditions. When plants are crowded, stooling cannot occur
to any marked degree, and the crop is rendered helpless in attempts
to adapt itself to surrounding conditions.
In general the rule may be laid down that a little more than one
half as much seed should be used in dry-farm districts with an
annual rainfall of about fifteen inches than is used in humid
districts. That is, as against the customary five pecks of wheat
used per acre in humid countries about three pecks or even two pecks
should be used on dry-farms. Merrill recommends the seeding of oats
at the rate of about three pecks per acre; of barley, about three
pecks; of rye, two pecks; of alfalfa, six pounds; of corn, two
kernels to the hill, and other crops in the same proportion. No
invariable rule can be laid down for perfect germination. A small
quantity of seed is usually sufficient; but where germination
frequently fails in part, more seed must be used. If the stand is
too thick at the beginning of the growing season, it must be
harrowed out. Naturally, the quantity of seed to be used should be
based on the number of kernels as well as on the weight. For
instance, since the larger the individual wheat kernels the fewer in
a bushel, fewer plants would be produced from a bushel of large than
from a bushel of small seed wheat. The size of the seed in
determining the amount for sowing is often important and should be
determined by some simple method, such as counting the seeds
required to fill a small bottle.
Method of sowing
There should really be no need of discussing the method of sowing
were it not that even at this day there are farmers in the dry-farm
district who sow by broadcasting and insist upon the superiority of
this method. The broadcasting of seed has no place in any system of
scientific agriculture, least of all in dry-farming, where success
depends upon the degree with which all conditions are controlled. In
all good dry-farm practice seed should be placed in rows, preferably
by means of one of the numerous forms of drill seeders found upon
the market. The advantages of the drill are almost self-evident. It
permits uniform distribution of the seed, which is indispensable for
success on soils that receive limited rainfall. The seed may be
placed at an even depth, which is very necessary, especially in fall
sowing, where the seed depends for proper germination upon the
moisture already stored in the soil. The deep seeding often
necessary under dry-farm conditions makes the drill indispensable.
Moreover, Hunt has explained that the drill furrows themselves have
definite advantages. During the winter the furrows catch the snow,
and because of the protection thus rendered, the seed is less likely
to be heaved out by repeated freezing and thawing. The drill furrow
also protects to a certain extent against the drying action of winds
and in that way, though the furrows are small, they aid materially
in enabling the young plant to pass through the winter successfully.
The rains of fall and spring are accumulated in the furrows and made
easily accessible to plants. Moreover, many of the drills have
attachments whereby the soil is pressed around the seed and the
topsoil afterwards stirred to prevent evaporation. This permits of a
much more rapid and complete germination. The drill, the advantages
of which were taught two hundred years ago by Jethro Tull, is one of
the most valuable implements of modern agriculture. On dry-farms it
is indispensable. The dry-farmer should make a careful study of the
drills on the market and choose such as comply with the principles
of the successful prosecution of dry-farming. Drill culture is the
only method of sowing that can be permitted if uniform success is
desired.
The care of the crop
Excepting the special treatment for soil-moisture conservation,
dry-farm crops should receive the treatment usually given crops
growing under humid conditions. The light rains that frequently fall
in autumn sometimes form a crust on the top of the soil, which
hinders the proper germination and growth of the fall-sown crop. It
may be necessary, therefore, for the farmer to go over the land in
the fall with a disk or more preferably with a corrugated roller.
Ordinarily, however, after fall sowing there is no further need of
treatment until the following spring. The spring treatment is of
considerably more importance, for when the warmth of spring and
early summer begins to make itself felt, a crust forms over many
kinds of dry-farm soils. This is especially true where the soil is
of the distinctively arid kind and poor in organic matter. Such a
crust should be broken early in order to give the young plants a
chance to develop freely. This may be accomplished, as above stated,
by the use of a disk, corrugated roller, or ordinary smoothing
harrow.
When the young grain is well under way, it may be found to be too
thick. If so, the crop may be thinned by going over the field with a
good irontooth harrow with the teeth so set as to tear out a portion
of the plants. This treatment may enable the remaining plants to
mature with the limited amount of moisture in the soil.
Paradoxically, if the crop seems to be too thin in the spring,
harrowing may also be of service. In such a case the teeth should be
slanted backwards and the harrowing done simply for the purpose of
stirring the soil without injury to the plant, to conserve the
moisture stored in the soil and to accelerate the formation of
nitrates.--The conserved moisture and added fertility will
strengthen the growth and diminish the water requirements of the
plants, and thus yield a larger crop. The iron-tooth harrow is a
very useful implement on the dry-farm when the crops are young.
After the plants are up so high that the harrow cannot be used on
them no special care need be given them, unless indeed they are
cultivated crops like corn or potatoes which, of course, as
explained in previous chapters, should receive continual
cultivation.
Harvesting
The methods of harvesting crops on dry-farms are practically those
for farms in humid districts. The one great exception may be the use
of the header on the grain farms of the dry-farm sections. The
header has now become well-nigh general in its use. Instead of
cutting and binding the grain, as in the old method, the heads are
simply cut off and piled in large stacks which later are threshed.
The high straw which remains is plowed under in the fall and helps
to supply the soil with organic matter. The maintenance of dry-farms
for over a generation without the addition of manures has been made
possible by the organic matter added to the soil in the decay of the
high vigorous straw remaining after the header. In fact, the changes
occurring in the soil in connection with the decaying of the header
stubble appear to have actually increased the available fertility.
Hundreds of Utah dry wheat farms during the last ten or twelve years
have increased in fertility, or at least in productive power, due
undoubtedly to the introduction of the header system of harvesting.
This system of harvesting also makes the practice of fallowing much
more effective, for it helps maintain the organic matter which is
drawn upon by the fallow seasons. The header should be used wherever
practicable. The fear has been expressed that the high header straw
plowed under will make the soil so loose as to render proper sowing
difficult and also, because of the easy circulation of air in the
upper soil layers, cause a large loss of soil-moisture. This fear
has been found to be groundless, for wherever the header straw has
been plowed under; especially in connection with fallowing, the soil
has been benefited.
Rapidity and economy in harvesting are vital factors in dry-farming,
and new devices are constantly being offered to expedite the work.
Of recent years the combined harvester and thresher has come into
general use. It is a large header combined with an ordinary
threshing machine. The grain is headed and threshed in one operation
and the sacks dropped along the path of the machine. The straw is
scattered over the field where it belongs.
All in all, the question of sowing, care of crop, and harvesting may
be answered by the methods that have been so well developed in
countries of abundant rainfall, except as new methods may be
required to offset the deficiency in the rainfall which is the
determining condition of dry-farming.
CHAPTER XII
CROPS FOR DRY-FARMING
The work of the dry-farmer is only half done when the soil has been
properly prepared, by deep plowing, cultivation, fallowing, for the
planting of the crop. The choice of the crop, its proper seeding,
and its correct care and harvesting are as important as rational
soil treatment in the successful pursuit of dry-farming. It is true
that in general the kinds of crops ordinarily cultivated in humid
regions are grown also on arid lands, but varieties especially
adapted to the prevailing dry-farm conditions must be used if any
certainty of harvest is desired. Plants possess a marvelous power of
adaptation to environment, and this power becomes stronger as
successive generations of plants are grown under the given
conditions. Thus, plants which have been grown for long periods of
time in countries of abundant rainfall and characteristic humid
climate and soil yield well under such conditions, but usually
suffer and die or at best yield scantily if planted in hot rainless
countries with deep soils. Yet, such plants, if grown year after
year under arid conditions, become accustomed to warmth and dryness
and in time will yield perhaps nearly as well or it may be better in
their new surroundings. The dry-farmer who looks for large harvests
must use every care to secure varieties of crops that through
generations of breeding have become adapted to the conditions
prevailing on his farm. Home-grown seeds, if grown properly, are
therefore of the highest value. In fact, in the districts where
dry-farming has been practiced longest the best yielding varieties
are, with very few exceptions, those that have been grown for many
successive years on the same lands. The comparative newness of the
attempts to produce profitable crops in the present dry-farming
territory and the consequent absence of home-grown seed has rendered
it wise to explore other regions of the world, with similar climatic
conditions, but long inhabited, for suitable crop varieties. The
United States Department of Agriculture has accomplished much good
work in this direction. The breeding of new varieties by scientific
methods is also important, though really valuable results cannot be
expected for many years to come. When results do come from breeding
experiments, they will probably be of the greatest value to the
dry-farmer. Meanwhile, it must be acknowledged that at the present,
our knowledge of dry-farm crops is extremely limited. Every year
will probably bring new additions to the list and great improvements
of the crops and varieties now recommended. The progressive
dry-farmer should therefore keep in close touch with state and
government workers concerning the best varieties to use.
Moreover, while the various sections of the dry-farming territory
are alike in receiving a small amount of rainfall, they are widely
different in other conditions affecting plant growth, such as soils,
winds, average temperature, and character and severity of the
winters. Until trials have been made in all these varying
localities, it is not safe to make unqualified recommendations of
any crop or crop variety. At the present we can only say that for
dry-farm purposes we must have plants that will produce the maximum
quantity of dry matter with the minimum quantity of water; and that
their periods of growth must be the shortest possible. However,
enough work has been done to establish some general rules for the
guidance of the dry-farmer in the selection of crops. Undoubtedly,
we have as yet had only a glimpse of the vast crop possibilities of
the dry-farming territory in the United States, as well as in other
countries.
Wheat
Wheat is the leading dry-farm crop. Every prospect indicates that it
will retain its preŽminence. Not only is it the most generally
used cereal, but the world is rapidly learning to depend more and
more upon the dry-farming areas of the world for wheat production.
In the arid and semiarid regions it is now a commonly accepted
doctrine that upon the expensive irrigated lands should be grown
fruits, vegetables, sugar beets, and other intensive crops, while
wheat, corn, and other grains and even much of the forage should be
grown as extensive crops upon the non-irrigated or dry-farm lands.
It is to be hoped that the time is near at hand when it will be a
rarity to see grain grown upon irrigated soil, providing the
climatic conditions permit the raising of more extensive crops.
In view of the present and future greatness of the wheat crop on
semiarid lands, it is very important to secure the varieties that
will best meet the varying dry-farm conditions. Much has been done
to this end, but more needs to be done. Our knowledge of the best
wheats is still fragmentary. This is even more true of other
dry-farm crops. According to Jardine, the dry-farm wheats grown at
present in the United States may be classificd as follows:--
I. Hard spring wheats:
(a) Common
(b) Durum
II. Winter wheats:
(a) Hard wheats (Crimean)
(b) Semihard wheats (Intermountain)
(c) Soft wheats (Pactfic)
The common varieties of hard _spring wheats _are grown principally
in districts where winter wheats have not as yet been successful;
that is, in the Dakotas, northwestern Nebraska, and other localities
with long winters and periods of alternate thawing and severe
freezing. The superior value of winter wheat has been so clearly
demonstrated that attempts are being made to develop in every
locality winter wheats that can endure the prevailing climatic
conditions. Spring wheats are also grown in a scattering way and in
small quantities over the whole dry-farm territory. The two most
valuable varieties of the common hard spring wheat are Blue Stem and
Red Fife, both well-established varieties of excellent milling
qualities, grown in immense quantities in the Northeastern corner of
the dry-farm territory of the United States and commanding the best
prices on the markets of the world. It is notable that Red Fife
originated in Russia, the country which has given us so many good
dry-farm crops.
The durum wheats or macaroni wheats, as they are often called, are
also spring wheats which promise to displace all other spring
varieties because of their excellent yields under extreme dry-farm
conditions. These wheats, though known for more than a generation
through occasional shipments from Russia, Algeria, and Chile, were
introduced to the farmers of the United States only in 1900, through
the explorations and enthusiastic advocacy of Carleton of the United
States Department of Agriculture. Since that time they have been
grown in nearly all the dryfarm states and especially in the Great
Plains area. Wherever tried they have yielded well, in some cases as
much as the old established winter varieties. The extreme hardness
of these wheats made it difficult to induce the millers operating
mills fitted for grinding softer wheats to accept them for
flourmaking purposes. This prejudice has, however, gradually
vanished, and to-day the durum wheats are in great demand,
especially for blending with the softer wheats and for the making of
macaroni. Recently the popularity of the durum wheats among the
farmers has been enhanced, owing to the discovery that they are
strongly rust resistant.
The _winter wheats, _as has been repeatedly suggested in preceding
chapters, are most desirable for dry-farm purposes, wherever they
can be grown, and especially in localities where a fair
precipitation occurs in the winter and spring. The hard winter
wheats are represented mainly by the Crimean group, the chief
members of which are Turkey, Kharkow, and Crimean. These wheats also
originated in Russia and are said to have been brought to the United
States a generation ago by Mennonite colonists. At present these
wheats are grown chiefly in the central and southern parts of the
Great Plains area and in Canada, though they are rapidly spreading
over the intermountain country. These are good milling wheats of
high gluten content and yielding abundantly under dry-farm
conditions. It is quite clear that these wheats will soon displace
the older winter wheats formerly grown on dry-farms. Turkey wheat
promises to become the leading dry-farm wheat. The semisoft winter
wheats are grown chiefly in the intermountain country. They are
represented by a very large number of varieties, all tending toward
softness and starchiness. This may in part be due to climatic, soil,
and irrigation conditions, but is more likely a result of inherent
qualities in the varieties used. They are rapidly being displaced by
hard varieties.
The group of soft winter wheats includes numerous varieties grown
extensively in the famous wheat districts of California, Oregon,
Washington, and northern Idaho. The main varieties are Red Russian
and Palouse Blue Stem, in Washington and Idaho, Red Chaff and Foise
in Oregon, and Defiance, Little Club, Sonora, and White Australian
in California. These are all soft, white, and rather poor in gluten.
It is believed that under given climatic, soil, and cultural
conditions, all wheat varieties will approach one type, distinctive
of the conditions in question, and that the California wheat type is
a result of prevailing unchangeable conditions. More researeh is
needed, however, before definite principles can be laid down
concerning the formation of distinctive wheat types in the various
dry-farm sections. Under any condition, a change of seed, keeping
improvement always in view, should be baneficial.
Jardine has reminded the dry-farmers of the United States that
before the production of wheat on the dry-farms can reach its full
possibilities under any acreage, sufficient quantities must be grown
of a few varieties to affect the large markets. This is especially
important in the intermountain country where no uniformity exists,
but the warning should be heeded also by the Pacific coast and Great
Plains wheat areas. As soon as the best varieties are found they
should displace the miscellaneous collection of wheat varieties now
grown. The individual farmer can be a law unto himself no more in
wheat growing than in fruit growing, if he desires to reap the
largest reward of his efforts. Only by uniformity of kind and
quality and large production will any one locality impress itself
upon the markets and create a demand. The changes now in progress by
the dry-farmers of the United States indicate that this lesson has
been taken to heart. The principle is equally important for all
countries where dry-farming is practiced.
Other small grains
_Oats _is undoubtedly a coming dry-farm crop. Several varieties have
been found which yield well on lands that receive an average annual
rainfall of less than fifteen inches. Others will no doubt be
discovered or developed as special attention is given to dry-farm
oats. Oats occurs as spring and winter varieties, but only one
winter variety has as yet found place in the list of dry-farm crops.
The leading; spring varieties of oats are the Sixty-Day, Kherson,
Burt, and Swedish Select. The one winter variety, which is grown
chiefly in Utah, is the Boswell, a black variety originally brought
from England about 1901.
_Barley, _like the other common grains, occurs in varieties that
grow well on dry-farms. In comparison with wheat very little seareh
has been made for dry-farm barleys, and, naturally, the list of
tested varieties is very small. Like wheat and oats, barley occurs
in spring and winter varieties, but as in the case of oats only one
winter variety has as yet found its way into the approved list of
dry-farm crops. The best dry-farm spring barleys are those belonging
to the beardless and hull-less types, though the more common
varieties also yield well, especially the six-rowed beardless
barley. The winter variety is the Tennessee Winter, which is already
well distributed over the Great Plains district.
_Rye _is one of the surest dry-farm crops. It yields good crops of
straw and grain, both of which are valuable stock foods. In fact,
the great power of rye to survive and grow luxuriantly under the
most trying dry-farm conditions is the chief objection to it. Once
started, it is hard to eradicate. Properly cultivated and used
either as a stock feed or as green manure, it is very valuable. Rye
occurs as both spring and winter varieties. The winter varieties are
usually most satisfactory.
Carleton has recommended _emmer _as a crop peculiarly adapted to
semiarid conditions. Emmer is a species of wheat to the berries of
which the chaff adheres very closely. It is highly prized as a stock
feed. In Russia and Germany it is grown in very large quantities. It
is especially adapted to arid and semiarid conditions, but will
probably thrive best where the winters are dry and summers wet. It
exists as spring and winter varieties. is with the other small
grains, the success of emmer will depend largely upon the
satisfactory development of winter varieties.
Corn
Of all crops yet tried on dry-farms, corn is perhaps the most
uniformly successful under extreme dry conditions. If the soil
treatment and planting have been right, the failures that have been
reported may invariably be traced to the use of seed which had not
been acclimated. The American Indians grow corn which is excellent
for dry-farm purposes; many of the western farmers have likewise
produced strains that use the minimum of moisture, and, moreover,
corn brought from humid sections adapts itself to arid conditions in
a very few years. Escobar reports a native corn grown in Mexico with
low stalks and small ears that well endures desert conditions. In
extremely dry years corn does not always produce a profitable crop
of seed, but the crop as a whole, for forage purposes, seldom fails
to pay expenses and leave a margin for profit. In wetter years there
is a corresponding increase of the corn crop. The dryfarming
territory does not yet realize the value of corn as a dry-farm crop.
The known facts concerning corn make it safe to predict, however,
that its dry farm acreage will increase rapidly, and that in time it
will crowd the wheat crop for preŽminence.
Sorghums
Among dry-farm crops not popularly known are the sorghums, which
promise to become excellent yielders under arid conditions. The
sorghums are supposed to have come grown the tropical sections of
the globe, but they are now scattered over the earth in all climes.
The sorghums have been known in the United States for over half a
century, but it was only when dry-farming began to develop so
tremendously that the drouth-resisting power of the sorghums was
recalled. According to Ball, the sorghums fall into the following
classes:--
THE SORGHUMS
1. Broom corns
2. Sorgas or sweet sorghums
3. Kafirs
4. Durras
The broom corns are grown only for their brush, and are not
considered in dry-farming; the sorgas for forage and sirups, and are
especially adapted for irrigation or humid conditions, though they
are said to endure dry-farm conditions better than corn. The Kafirs
are dry-farm crops and are grown for grain and forage. This group
includes Red Kafir, White Kafir, Black-hulled White Kafir, and White
Milo, all of which are valuable for dry-farming. The Durras are
grown almost exclusively for seed and include Jerusalem corn, Brown
Durra, and Milo. The work of Ball has made Milo one of the most
important dry-farm crops. As improved, the crop is from four to four
and a half feet high, with mostly erect heads, carrying a large
quantity of seeds. Milo is already a staple crop in parts of Texas,
Oklahoma, Kansas, and New Mexico. It has further been shown to be
adapted to conditions in the Dakotas, Nebraska, Colorado, Arizona,
Utah, and Idaho. It will probably be found, in some varietal form,
valuable over the whole dry-farm territory where the altitude is not
too high and the average temperature not too low.
It has yielded an average of forty bushels of seed to the acre.
Lucern or alfalfa
Next to human intelligence and industry, alfalfa has probably been
the chief factor in the development of the irrigated West. It has
made possible a rational system of agriculture, with the live-stock
industry and the maintenance of soil fertility as the central
considerations. Alfalfa is now being recognized as a desirable crop
in humid as well as in irrigated sections, and it is probable that
alfalfa will soon become the chief hay crop of the United States.
Originally, lucern came from the hot dry countries of Asia, where it
supplied feed to the animals of the first historical peoples.
Moreover, its long; tap roots, penetrating sometimes forty or fifty
feet into the ground, suggest that lucern may make ready use of
deeply stored soil-moisture. On these considerations, alone, lucern
should prove itself a crop well suited for dry-farming. In fact, it
has been demonstrated that where conditions are favorable, lucern
may be made to yield profitable crops under a rainfall between
twelve and fifteen inches. Alfalfa prefers calcareous loamy soils;
sandy and heavy clay soils are not so well adapted for successful
alfalfa production. Under dry-farm conditions the utmost care must
be used to prevent too thick seeding. The vast majority of alfalfa
failures on dry-farms have resulted from an insufficient supply of
moisture for the thickly planted crop. The alfalfa field does not
attain its maturity until after the second year, and a crop which
looks just right the second year will probably be much too thick the
third and fourth years. From four to six pounds of seed per acre are
usually ample. Another main cause of failure is the common idea that
the lucern field needs little or no cultivation, when, in fact, the
alfalfa field should receive as careful soil treatment as the wheat
field. Heavy, thorough disking in spring or fall, or both, is
advisable, for it leaves the topsoil in a condition to prevent
evaporation and admit air. In Asiatic and North African countries,
lucern is frequently cultivated between rows throughout the hot
season. This has been tried by Brand in this country and with very
good results. Since the crop should always be sown with a drill, it
is comparatively easy to regulate the distance between the rows so
that cultivating implements may be used. If thin seeding and
thorough soil stirring are practiced, lucern usually grows well, and
with such treatment should become one of the great dry-farm crops.
The yield of hay is not large, but sufficient to leave a comfortable
margin of profit. Many farmers find it more profitable to grow
dry-farm lucern for seed. In good years from fifty to one hundred
and fifty dollars may be taken from an acre of lucern seed. However,
at the present, the principles of lucern seed production are not
well established, and the seed crop is uncertain.
Alfalfa is a leguminous crop and gathers nitrogen from the air. It
is therefore a good fertilizer. The question of soil fertility will
become more important with the passing of the years, and the value
of lucern as a land improver will then be more evident than it is
to-day.
Other leguminous crops
The group of leguminous or pod-bearing crops is of great importance;
first, because it is rich in nitrogenous substances which are
valuable animal foods, and, secondly, because it has the power of
gathering nitrogen from the air, which can be used for maintaining
the fertility of the soil. Dry-farming will not be a wholly safe
practice of agriculture until suitable leguminous crops are found
and made part of the crop system. It is notable that over the whole
of the dry-farm territory of this and other countries wild
leguminous plants flourish. That is, nitrogen-gathering plants are
at work on the deserts. The farmer upsets this natural order of
things by cropping the land with wheat and wheat only, so long as
the land will produce profitably. The leguminous plants native to
dry-farm areas have not as yet been subjected to extensive economic
study, and in truth very little is known concerning leguminous
plants adapted to dry-farming.
In California, Colorado, and other dry-farm states the field pea has
been grown with great profit. Indeed it has been found much more
profitable than wheat production. The field bean, likewise, has been
grown successfully under dry-farm conditions, under a great variety
of climates. In Mexico and other southern climates, the native
population produce large quantities of beans upon their dry lands.
Shaw suggests that sanfoin, long famous for its service to European
agriculture, may be found to be a profitable dry-farm crop, and that
sand vetch promises to become an excellent dry-farm crop. It is very
likely, however, that many of the leguminous crops which have been
developed under conditions of abundant rainfall will be valueless on
dry-farm lands. Every year will furnish new and more complete
information on this subject. Leguminous plants will surely become
important members of the association of dry-farm crops.
Trees and shrubs
So far, trees cannot be said to be dry-farm crops, though facts are
on record that indicate that by the application of correct dry-farm
principles trees may be made to grow and yield profitably on
dry-farm lands. Of course, it is a well-known fact that native trees
of various kinds are occasionally found growing on the deserts,
where the rainfall is very light and the soil has been given no
care. Examples of such vegetation are the native cedars found
throughout the Great Basin region and the mesquite tree in Arizona
and the Southwest. Few farmers in the arid region have as yet
undertaken tree culture without the aid of irrigation.
At least one peach orchard is known in Utah which grows under a
rainfall of about fifteen inches without irrigation and produces
regularly a small crop of most delicious fruit. Parsons describes
his Colorado dry-farm orchard in which, under a rainfall of almost
fourteen inches, he grows, with great profit, cherries, plums, and
apples. A number of prospering young orchards are growing without
irrigation in the Great Plains area. Mason discovered a few years
ago two olive orchards in Arizona and the Colorado desert which,
planted about fourteen years previously, were thriving under an
annual rainfall of eight and a half and four and a half inches,
respectively. These olive orchards had been set out under canals
which later failed. Such attested facts lead to the thought that
trees may yet take their place as dry-farm crops. This hope is
strengthened when it is recalled that the great nations of
antiquity, living in countries of low rainfall, grew profitably and
without irrigation many valuable trees, some of which are still
cultivated in those countries. The olive industry, for example, is
even now being successfully developed by modern methods in Asiatic
and African sections, where the average annual rainfall is under ten
inches. Since 1881, under French management, the dry-farm olive
trees around Tunis have increased from 45,000 to 400,000
individuals. Mason and also Aaronsohn suggest as trees that do well
in the arid parts of the old world the so-called "Chinese date" or
JuJube tree, the sycamore fig, and the Carob tree, which yields the
"St. John's Bread" so dear to childhood.
Of this last tree, Aaronsolm says that twenty trees to the acre,
under a rainfall of twelve inches, will produce 8000 pounds of fruit
containing 40 per cent of sugar and 7 to 8 per cent of protein. This
surpasses the best harvest of alfalfa. Kearnley, who has made a
special study of dry-land olive culture in northern Africa, states
that in his belief a large variety of fruit trees may be found which
will do well under arid and semiarid conditions, and may even yield
more profit than the grains.
It is also said that many shade and ornamental and other useful
plants can be grown on dry-farms; as, for instance, locust, elm,
black walnut, silverpoplar, catalpa, live oak, black oak, yellow
pine, red spruce, Douglas fir, and cedar.
The secret of success in tree growing on dry-farms seems to lie,
first, in planting a few trees per acre,--the distance apart should
be twice the ordinary distance,--and, secondly, in applying
vigorously and unceasingly the established principles of soil
cultivation. In a soil stored deeply with moisture and properly
cultivated, most plants will grow. If the soil has not been
carefully fallowed before planting, it may be necessary to water the
young trees slightly during the first two seasons.
Small fruits have been tried on many farms with great success.
Plums, currants, and gooseberries have all been successful. Grapes
grow and yield well in many dry-farm districts, especially along the
warm foothills of the Great Basin. Tree growing on dry-farm lands is
not yet well established and, therefore, should be undertaken with
great care. Varieties accustomed to the climatic environment should
be chosen, and the principles outlined in the preceding pages should
be carefully used.
Potatoes
In recent years, potatoes have become one of the best dry-farm
crops. Almost wherever tried on lands under a rainfall of twelve
inches or more potatoes have given comparatively large yields.
To-day, the growing of dry-farm potatoes is becoming an important
industry. The principles of light seeding and thorough cultivation
are indispensable for success. Potatoes are well adapted for use in
rotations, where summer fallowing is not thought desirable.
Macdonald enumerates the following as the best varieties at present
used on dry-farms: Ohio, Mammoth, Pearl, Rural New Yorker, and
Burbank.
Miscellaneous
A further list of dry-farm crops would include representatives of
nearly all economic plants, most of them tried in small quantity in
various localities. Sugar beets, vegetables, bulbous plants, etc.,
have all been grown without irrigation under dry-farm conditions.
Some of these will no doubt be found to be profitable and will then
be brought into the commercial scheme of dry-farming.
Meanwhile, the crop problems of dry-farming demand that much careful
work be done in the immediate future by the agencies having such
work in charge. The best varieties of crops already in profitable
use need to be determined. More new plants from all parts of the
world need to be brought to this new dry-farm territory and tried
out. Many of the native plants need examination with a view to their
economic use. For instance, the sego lily bulbs, upon which the Utah
pioneers subsisted for several seasons of famine, may possibly be
made a cultivated crop. Finally, it remains to be said that it is
doubtful wisdom to attempt to grow the more intensive crops on
dry-farms. Irrigation and dry-farming will always go together. They
are supplementary systems of agriculture in arid and semiarid
regions. On the irrigated lands should be grown the crops that
require much labor per acre and that in return yield largely per
acre. New crops and varieties should besought for the irrigated
farms. On the dry-farms should be grown the crops that can be
handled in a large way and at a small cost per acre, and that yield
only moderate acre returns. By such cooperation between irrigation
and dry-farming will the regions of the world with a scanty rainfall
become the healthiest, wealthiest, happiest, and most populous on
earth.
CHAPTER XIII
THE COMPOSITION OF DRY-FARM CROPS
The acre-yields of crops on dry-farms, even under the most favorable
methods of culture, are likely to be much smaller than in humid
sections with fertile soils. The necessity for frequent fallowing or
resting periods over a large portion of the dry-farm territory
further decreases the average annual yield. It does not follow from
this condition that dry-farming is less profitable than humid-or
irrigation-farming, for it has been fully demonstrated that the
profit on the investment is as high under proper dry-farming as
under any other similar generally adopted system of farming in any
part of the world. Yet the practice of dry-farming would appear to
be, and indeed would be, much more desirable could the crop yield be
increased. The discovery of any condition which will offset the
small annual yields is, therefore, of the highest importance to the
advancement of dry-farming. The recognition of the superior quality
of practically all crops grown without irrigation under a limited
rainfall has done much to stimulate faith in the great
profitableness of dry-farming. As the varying nature of the
materials used by man for food, clothing, and shelter has become
more clearly understood, more attention has been given to the
valuation of commercial products on the basis of quality as well as
of quantity. Sugar beets, for instance, are bought by the sugar
factories under a guarantee of a minimum sugar content; and many
factories of Europe vary the price paid according to the sugar
contained by the beets. The millers, especially in certain parts of
the country where wheat has deteriorated, distinguish carefully
between the flour-producing qualities of wheats from various
sections and fix the price accordingly. Even in the household,
information concerning the real nutritive value of various foods is
being sought eagerly, and foods let down to possess the highest
value in the maintenance of life are displacing, even at a higher
cost, the inferior products. The quality valuation is, in fact,
being extended as rapidly as the growth of knowledge will permit to
the chief food materials of commerce. As this practice becomes fixed
the dry-farmer will be able to command the best market prices for
his products, for it is undoubtedly true that from the point of view
of quality, dry-farm food products may be placed safely in
competition with any farm products on the markets of the world.
Proportion of plant parts
It need hardly be said, after the discussions in the preceding
chapters, that the nature of plant growth is deeply modified by the
arid conditions prevailing in dry-farming. This shows itself first
in the proportion of the various plant parts, such as roots, stems,
leaves, and seeds. The root systems of dry-farm crops are generally
greatly developed, and it is a common observation that in adverse
seasons the plants that possess the largest and most vigorous roots
endure best the drouth and burning heat. The first function of the
leaves is to gather materials for the building and strengthening of
the roots, and only after this has been done do the stems lengthen
and the leaves thicken. Usually, the short season is largely gone
before the stem and leaf growth begins, and, consequently, a
somewhat dwarfed appearance is characteristic of dry-farm crops. The
size of sugar beets, potato tubers, and such underground parts
depends upon the available water and food supply when the plant has
established a satisfactory root and leaf system. If the water and
food are scarce, a thin beet results; if abundant, a well-filled
beet may result.
Dry-farming is characterized by a somewhat short season. Even if
good growing weather prevails, the decrease of water in the soil has
the effect of hastening maturity. The formation of flowers and seed
begins, therefore, earlier and is completed more quickly under arid
than under humid conditions. Moreover, and resulting probably from
the greater abundance of materials stored in the root system, the
proportion of heads to leaves and stems is highest in dry-farm
crops. In fact, it is a general law that the proportion of heads to
straw in grain crops increases as the water supply decreases. This
is shown very well even under humid or irrigation conditions when
different seasons or different applications of irrigation water are
compared. For instance, Hall quotes from the Rothamsted experiments
to the effect that in 1879, which was a wet year (41 inches), the
wheat crop yielded 38 pounds of grain for every 100 pounds of straw;
whereas, in 1893, which was a dry year (23 inches), the wheat crop
yielded 95 pounds of grain to every 100 pounds of straw. The Utah
station likewise has established the same law under arid conditions.
In one series of experiments it was shown as an average of three
years' trial that a field which had received 22.5 inches of
irrigation water produced a wheat crop that gave 67 pounds of grain
to every 100 pounds of straw; while another field which received
only 7.5 inches of irrigation water produced a crop that gave 100
pounds of grain for every 100 pounds of straw. Since wheat is grown
essentially for the grain, such a variation is of tremendous
importance. The amount of available water affects every part of the
plant. Thus, as an illustration, Carleton states that the per cent
of meat in oats grown in Wisconsin under humid conditions was 67.24,
while in North Dakota, Kansas, and Montana, under arid and semiarid
conditions, it was 71.51. Similar variations of plant parts may be
observed as a direct result of varying the amount of available
water. In general then, it may be said that the roots of dry-farm
crops are well developed; the parts above ground somewhat dwarfed;
the proportion of seed to straw high, and the proportion of meat or
nutritive materials in the plant parts likewise high.
The water in dry-farm crops
One of the constant constituents of all plants and plant parts is
water. Hay, flour, and starch contain comparatively large quantities
of water, which can be removed only by heat. The water in green
plants is often very large. In young lucern, for instance, it
reaches 85 per cent, and in young peas nearly 90 per cent, or more
than is found in good cow's milk. The water so held by plants has no
nutritive value above ordinary water. It is, therefore, profitable
for the consumer to buy dry foods. In this particular, again,
dry-farm crops have a distinct advantage: During growth there is not
perhaps a great difference in the water content of plants, due to
climatic differences, but after harvest the drying-out process goes
on much more completely in dry-farm than in humid districts. Hay,
cured in humid regions, often contains from 12 to 20 per cent of
water; in arid climates it contains as little as 5 per cent and
seldom more than 12 per cent. The drier hay is naturally more
valuable pound for pound than the moister hay, and a difference in
price, based upon the difference in water content, is already being
felt in certain sections of the West.
The moisture content of dry-farm wheat, the chief dry-farm crop, is
even more important. According to Wiley the average water content of
wheat for the United States is 10.62 per cent, ranging from 15 to 7
per cent. Stewart and Greaves examined a large number of wheats
grown on the dry-farms of Utah and found that the average per cent
of water in the common bread varieties was 8.46 and in the durum
varieties 8.89. This means that the Utah dry-farm wheats transported
to ordinary humid conditions would take up enough water from the air
to increase their weight one fortieth, or 2.2 per cent, before they
reached the average water content of American wheats. In other
words, 1,000,000 bushels of Utah dry-farm wheat contain as much
nutritive matter as 1,025,000 bushels of wheat grown and kept under
humid conditions. This difference should be and now is recognized in
the prices paid. In fact, shrewd dealers, acquainted with the
dryness of dry-farm wheat, have for some years bought wheat from the
dry-farms at a slightly increased price, and trusted to the increase
in weight due to water absorption in more humid climates for their
profits. The time should be near at hand when grains and similar
products should be purchased upon the basis of a moisture test.
While it is undoubtedly true that dry-farm crops are naturally drier
than those of humid countries, yet it must also be kept in mind that
the driest dry-farm crops are always obtained where the summers are
hot and rainless. In sections where the precipitation comes chiefly
in the spring and summer the difference would not be so great.
Therefore, the crops raised on the Great Plains would not be so dry
as those raised in California or in the Great Basin. Yet, wherever
the annual rainfall is so small as to establish dry-farm conditions,
whether it comes in the winter or summer, the cured crops are drier
than those produced under conditions of a much higher rainfall, and
dry farmers should insist that, so far as possible in the future,
sales be based on dry matter.
The nutritive substances in crops
The dry matter of all plants and plant parts consists of three very
distinct classes of substances: First, ash or the mineral
constituents. Ash is used by the body in building bones and in
supplying the blood with compounds essential to the various life
processes. Second, protein or the substances containing the element
nitrogen. Protein is used by the body in making blood, muscle,
tendons, hair, and nails, and under certain conditions it is burned
within the body for the production of heat. Protein is perhaps the
most important food constituent. Third, non-nitrogenous substances,
including fats, woody fiber, and nitrogen-free extract, a name given
to the group of sugars, starehes, and related substances. These
substances are used by the body in the production of fat, and are
also burned for the production of heat. Of these valuable food
constituents protein is probably the most important, first, because
it forms the most important tissues of the body and, secondly,
because it is less abundant than the fats, starches, and sugars.
Indeed, plants rich in protein nearly always command the highest
prices.
The composition of any class of plants varies considerably in
different localities and in different seasons. This may be due to
the nature of the soil, or to the fertilizer applied, though
variations in plant composition resulting from soil conditions are
comparatively small. The greater variations are almost wholly the
result of varying climate and water supply. As far as it is now
known the strongest single factor in changing the composition of
plants is the amount of water available to the growing plant.
Variations due to varying water supply
The Utah station has conducted numerous experiments upon the effect
of water upon plant composition. The method in every case has been
to apply different amounts of water throughout the growing season on
contiguous plats of uniform land. [Lengthy table deleated from this
edition.] Even a casual study of . . . [the results show] that the
quantity of water used influenced the composition of the plant
parts. The ash and the fiber do not appear to be greatly influenced,
but the other constituents vary with considerable regularity with
the variations in the amount of irrigation water. The protein shows
the greatest variation. As the irrigation water is increased, the
percentage of protein decreases. In the case of wheat the variation
was over 9 per cent. The percentage of fat and nitrogen-free
extract, on the other hand, becomes larger as the water increases.
That is, crops grown with little water, as in dry-farming, are rich
in the important flesh-and blood-forming substance protein, and
comparatively poor in fat, sugar, stareh, and other of the more
abundant heat and fat-producing substances. This difference is of
tremendous importance in placing dry-farming products on the food
markets of the world. Not only seeds, tubers, and roots show this
variation, but the stems and leaves of plants grown with little
water are found to contain a higher percentage of protein than those
grown in more humid climates.
The direct effect of water upon the composition of plants has been
observed by many students. For instance, Mayer, working in Holland,
found that, in a soil containing throughout the season 10 per cent
of water, oats was produced containing 10.6 per cent of protein; in
soil containing 30 per cent of water, the protein percentage was
only 5.6 per cent, and in soil containing 70 per cent of water, it
was only 5.2 per cent. Carleton, in a study of analyses of the same
varieties of wheat grown in humid and semi-arid districts of the
United States, found that the percentage of protein in wheat from
the semiarid area was 14.4 per cent as against 11.94 per cent in the
wheat from the humid area. The average protein content of the wheat
of the United States is a little more than 12 per cent; Stewart and
Greaves found an average of 16.76 per cent of protein in Utah
dry-farm wheats of the common bread varieties and 17.14 per cent in
the durum varieties. The experiments conducted at Rothamsted,
England, as given by Hall, confirm these results. For example,
during 1893, a very dry year, barley kernels contained 12.99 per
cent of protein, while in 1894, a wet, though free-growing year, the
barley contained only 9.81 per cent of protein. Quotations might be
multiplied confirming the principle that crops grown with little
water contain much protein and little heat-and fat-producing
substances.
Climate and composition
The general climate, especially as regards the length of the growing
season and naturally including the water supply, has a strong effect
upon the composition of plants. Carleton observed that the same
varieties of wheat grown at Nephi, Utah, contained 16.61 per cent
protein; at Amarillo, Texas, 15.25 per cent; and at McPherson,
Kansas, a humid station, 13.04 per cent. This variation is
undoubtedly due in part to the varying annual precipitation but,
also, and in large part, to the varying general climatic conditions
at the three stations.
An extremely interesting and important experiment, showing the
effect of locality upon the composition of wheat kernels, is
reported by LeClerc and Leavitt. Wheat grown in 1905 in Kansas was
planted in 1906 in Kansas, California, and Texas In 1907 samples of
the seeds grown at these three points were planted side by side at
each of the three states All the crops from the three localities
were analyzed separately each year.
The results are striking and convincing. The original seed grown in
Kansas in 1905 contained 16.22 per cent of protein. The 1906 crop
grown from this seed in Kansas contained 19.13 per cent protein; in
California, 10.38 percent; and in Texas, 12.18 percent. In 1907 the
crop harvested in Kansas from the 1906 seed from these widely
separated places and of very different composition contained
uniformly somewhat more than 22 per cent of protein; harvested in
California, somewhat more than 11 per cent; and harvested in Texas,
about 18 per cent. In short, the composition of wheat kernels is
independent of the composition of the seed or the nature of the
soil, but depends primarily upon the prevailing climatic conditions,
including the water supply. The weight of the wheat per bushel, that
is, the average size and weight of the wheat kernel, and also the
hardness or flinty character of the kernels, were strongly affected
by the varying climatic conditions. It is generally true that
dry-farm grain weighs more per bushel than grain grown under humid
conditions; hardness usually accompanies a high protein content and
is therefore characteristic of dry-farm wheat. These notable lessons
teach the futility of bringing in new seed from far distant places
in the hope that better and larger crops may be secured. The
conditions under which growth occurs determine chiefly the nature of
the crop. It is a common experience in the West that farmers who do
not understand this principle send to the Middle West for seed corn,
with the result that great crops of stalks and leaves with no ears
are obtained. The only safe rule for the dry-farmer to follow is to
use seed which has been grown for many years under dry-farm
conditions.
A reason for variation in composition
It is possible to suggest a reason for the high protein content of
dry-farm crops. It is well known that all plants secure most of
their nitrogen early in the growing period. From the nitrogen,
protein is formed, and all young plants are, therefore, very rich in
protein. As the plant becomes older, little more protein is added,
but more and more carbon is taken from the air to form the fats,
starches, sugars, and other non-nitrogenous substances.
Consequently, the proportion or percentage of protein becomes
smaller as the plant becomes older. The impelling purpose of the
plant is to produce seed. Whenever the water supply begins to give
out, or the season shortens in any other way, the plant immediately
begins to ripen. Now, the essential effect of dry-farm conditions is
to shorten the season; the comparatively young plants, yet rich in
protein, begin to produce seed; and at harvest, seed, and leaves,
and stalks are rich in the flesh-and blood-forming element of
plants. In more humid countries plants delay the time of seed
production and thus enable the plants to store up more carbon and
thus reduce the percent of protein. The short growing season,
induced by the shortness of water, is undoubtedly the main reason
for the higher protein content and consequently higher nutritive
value of all dry-farm crops.
Nutritive value of dry-farm hay, straw, and flour
All the parts of dry-farm crops are highly nutritious. This needs to
be more clearly understood by the dry-farmers. Dry-farm hay, for
instance, because of its high protein content, may be fed with crops
not so rich in this element, thereby making a larger profit for the
farmer. Dry-farm straw often has the feeding value of good hay, as
has been demonstrated by analyses and by feeding tests conducted in
times of hay scarcity. Especially is the header straw of high
feeding value, for it represents the upper and more nutritious ends
of the stalks. Dry-farm straw, therefore, should be carefully kept
and fed to animals instead of being scattered over the ground or
even burned as is too often the case. Only few feeding experiments
having in view the relative feeding value of dry-farm crops have as
yet been made, but the few on record agree in showing the superior
value of dry-farm crops, whether fed singly or in combination.
The differences in the chemical composition of plants and plant
products induced by differences in the water-supply and climatic
environment appear in the manufactured products, such as flour,
bran, and shorts. Flour made from Fife wheat grown on the dry-farms
of Utah contained practically 16 per cent of protein, while flour
made from Fife wheat grown in Lorraine and the Middle West is
reported by the Maine Station as containing from 13.03 to 13.75 per
cent of protein. Flour made from Blue Stem wheat grown on the Utah
dry-farms contained 15.52 per cent of protein; from the same variety
grown in Maine and in the Middle West 11.69 and 11.51 per cent of
protein respectively. The moist and dry gluten, the gliadin and the
glutenin, all of which make possible the best and most nourishing
kinds of bread, are present in largest quantity and best proportion
in flours made from wheats grown under typical dry-farm conditions.
The by-products of the milling process, likewise, are rich in
nutritive elements.
Future Needs
It has already been pointed out that there is a growing tendency to
purchase food materials on the basis of composition. New discoveries
in the domains of plant composition and animal nutrition and the
improved methods of rapid and accurate valuation will accelerate
this tendency. Even now, manufacturers of food products print on
cartons and in advertising matter quality reasons for the superior
food values of certain articles. At least one firm produces two
parallel sets of its manufactured foods, one for the man who does
hard physical labor, and the other for the brain worker. Quality, as
related to the needs of the body, whether of beast or man, is
rapidly becoming the first question in judging any food material.
The present era of high prices makes this matter even more
important.
In view of this condition and tendency, the fact that dry-farm
products are unusually rich in the most valuable nutritive materials
is of tremendous importance to the development of dry-farming. The
small average yields of dry-farm crops do not look so small when it
is known that they command higher prices per pound in competition
with the larger crops of more humid climates. More elaborate
investigations should be undertaken to determine the quality of
crops grown in different dry-farm districts. As far as possible each
section, great or small, should confine itself to the growing of a
variety of each crop yielding well and possessing the highest
nutritive value. In that manner each section of the great dry-farm
territory would soon come to stand for some dependable special
quality that would compel a first-class market. Further, the
superior feeding value of dry-farm products should be thoroughly
advertised among the consumers in order to create a demand on the
markets for a quality valuation. A few years of such systematic
honest work would do much to improve the financial basis of
dry-farming.
CHAPER XIV
MAINTAINING THE SOIL FERTILITY
All plants when carefully burned leave a portion of ash, ranging
widely in quantity, averaging about 5 per cent, and often exceeding
10 per cent of the dry weight of the plant. This plant ash
represents inorganic substances taken from the soil by the roots. In
addition, the nitrogen of plants, averaging about 2 per cent and
often amounting to 4 per cent, which, in burning, passes off in
gaseous form, is also usually taken from the soil by the plant
roots. A comparatively large quantity of the plant is, therefore,
drawn directly from the soil. Among the ash ingredients are many
which are taken up by the plant simply because they are present in
the soil; others, on the other hand, as has been shown by numerous
classical investigations, are indispensable to plant growth. If any
one of these indispensable ash ingredients be absent, it is
impossible for a plant to mature on such a soil. In fact, it is
pretty well established that, providing the physical conditions and
the water supply are satisfactory, the fertility of a soil depends
largely upon the amount of available ash ingredients, or plant-food.
A clear distinction must be made between the_ total _and _available
_plant-food. The essential plant-foods often occur in insoluble
combinations, valueless to plants; only the plant-foods that are
soluble in the soil-water or in the juices of plant roots are of
value to plants. It is true that practically all soils contain all
the indispensable plant-foods; it is also true, however, that in
most soils they are present, as available plant-foods, in
comparatively small quantities. When crops are removed from the land
year after year, without any return being made, it naturally follows
that under ordinary conditions the amount of available plant-food is
diminished, with a strong probability of a corresponding diminution
in crop-producing power. In fact, the soils of many of the older
countries have been permanently injured by continuous cropping, with
nothing returned, practiced through centuries. Even in many of the
younger states, continuous cropping to wheat or other crops for a
generation or less has resulted in a large decrease in the crop
yield.
Practice and experiment have shown that such diminishing fertility
may be retarded or wholly avoided, first, by so working or
cultivating the soil as to set free much of the insoluble plant-food
and, secondly, by returning to the soil all or part of the
plant-food taken away. The recent development of the commercial
fertilizer industry is a response to this truth. It may be said
that, so far as the agricultural soils of the world are now known,
only three of the essential plant-foods are likely to be absent,
namely, potash, phosphoric acid, and nitrogen; of these, by far the
most important is nitrogen. The whole question of maintaining the
supply of plant-foods in the soil concerns itself in the main with
the supply of these three substances.
The persistent fertility of dry-farms
In recent years, numerous farmers and some investigators have stated
that under dry-farm conditions the fertility of soils is not
impaired by cropping without manuring. This view has been taken
because of the well-known fact that in localities where dry-farming
has been practiced on the same soils from twenty-five to forty-five
years, without the addition of manures, the average crop yield has
not only failed to diminish, but in most cases has increased. In
fact, it is the almost unanimous testimony of the oldest dry-farmers
of the United States, operating under a rainfall from twelve to
twenty inches, that the crop yields have increased as the cultural
methods have been perfected. If any adverse effect of the steady
removal of plant-foods has occurred, it has been wholly overshadowed
by other factors. The older dry-farms in Utah, for instance, which
are among the oldest of the country, have never been manured, yet
are yielding better to-day than they did a generation ago. Strangely
enough, this is not true of the irrigated farms, operating under
like soil and climatic conditions. This behavior of crop production
under dry-farm conditions has led to the belief that the question of
soil fertility is not an important one to dry-farmers. Nevertheless,
if our present theories of plant nutrition are correct, it is also
true that, if continuous cropping is practiced on our dry-farm soils
without some form of manuring, the time must come when the
productive power of the soils will be injured and the only recourse
of the farmer will be to return to the soils some of the plant-food
taken from it.
The view that soil fertility is not diminished by dry-farming
appears at first sight to be strengthened by the results obtained by
investigators who have made determinations of the actual plant-food
in soils that have long been dry-farmed. The sparsely settled
condition of the dry-farm territory furnishes as yet an excellent
opportunity to compare virgin and dry-farmed lands and which
frequently may be found side by side in even the older dry-farm
sections. Stewart found that Utah dry-farm soils, cultivated for
fifteen to forty years and never manured, were in many cases richer
in nitrogen than neighboring virgin lands. Bradley found that the
soils of the great dry-farm wheat belt of Eastern Oregon contained,
after having been farmed for a quarter of a century, practically as
much nitrogen as the adjoining virgin lands. These determinations
were made to a depth of eighteen inches. Alway and Trumbull, on the
other hand, found in a soil from Indian Head, Saskatchewan, that in
twenty-five years of cultivation the total amount of nitrogen had
been reduced about one third, though the alternation of fallow and
crop, commonly practiced in dry-farming, did not show a greater loss
of soil nitrogen than other methods of cultivation. It must be kept
in mind that the soil of Indian Head contains from two to three
times as much nitrogen as is ordinarily found in the soils of the
Great Plains and from three to four times as much as is found in the
soils of the Great Basin and the High Plateaus. It may be assumed,
therefore, that the Indian Head soil was peculiarly liable to
nitrogen losses. Headden, in an investigation of the nitrogen
content of Colorado soils, has come to the conclusion that arid
conditions, like those of Colorado, favor the direct accumulation of
nitrogen in soils. All in all, the undiminished crop yield and the
composition of the cultivated fields lead to the belief that
soil-fertility problems under dry-farm conditions are widely
different from the old well-known problems under humid conditions.
Reasons for dry-farming fertility
It is not really difficult to understand why the yields and,
apparently, the fertility of dry-farms have continued to increase
during the period of recorded dry-farm history--nearly half a
century.
First, the intrinsic fertility of arid as compared with humid soils
is very high. (See Chapter V.) The production and removal of many
successive bountiful crops would not have as marked an effect on
arid as on humid soils, for both yield and composition change more
slowly on fertile soils. The natural extraordinarily high fertility
of dry-farm soils explains, therefore, primarily and chiefly, the
increasing yields on dry-farm soils that receive proper cultivation.
The intrinsic fertility of arid soils is not alone sufficient to
explain the increase in plant-food which undoubtedly occurs in the
upper foot or two of cultivated dry-farm lands. In seeking a
suitable explanation of this phenomenon it must be recalled that the
proportion of available plant-food in arid soils is very uniform to
great depths, and that plants grown under proper dry-farm conditions
are deep rooted and gather much nourishment from the lower soil
layers. As a consequence, the drain of a heavy crop does not fall
upon the upper few feet as is usually the case in humid soils. The
dry-farmer has several farms, one upon the other, which permit even
improper methods of farming to go on longer than would be the case
on shallower soils.
The great depth of arid soils further permits the storage of rain
and snow water, as has been explained in previous chapters, to
depths of from ten to fifteen feet. As the growing season proceeds,
this water is gradually drawn towards the surface, and with it much
of the plant-food dissolved by the water in the lower soil layers.
This process repeated year after year results in a concentration in
the upper soil layers of fertility normally distributed in the soil
to the full depth reach by the soil-moisture. At certain seasons,
especially in the fall, this concentration may be detected with
greatest certainty. In general, the same action occurs in virgin
lands, but the methods of dry-farm cultivation and cropping which
permit a deeper penetration of the natural precipitation and a freer
movement of the soil-water result in a larger quantity of plant-food
reaching the upper two or three feet from the lower soil depths.
Such concentration near the surface, when it is not excessive,
favors the production of increased yields of crops.
The characteristic high fertility and great depth of arid soils are
probably the two main factors explaining the apparent increase of
the fertility of dry-farms under a system of agriculture which does
not include the practice of manuring. Yet, there are other
conditions that contribute largely to the result. For instance,
every cultural method accepted in dry-farming, such as deep plowing,
fallowing, and frequent cultivation, enables the weathering forces
to act upon the soil particles. Especially is it made easy for the
air to enter the soil. Under such conditions, the plant-food
unavailable to plants because of its insoluble condition is
liberated and made available. The practice of dry-farming is of
itself more conducive to such accumulation of available plant food
than are the methods of humid agriculture.
Further, the annual yield of any crop under conditions of
dry-farming is smaller than under conditions of high rainfall. Less
fertility is, therefore, removed by each crop and a given amount of
available fertility is sufficient to produce a large number of crops
without showing signs of deficiency. The comparatively small annual
yield of dry-farm crops is emphasized in view of the common practice
of summer fallowing, which means that the land is cropped only every
other year or possibly two years out of three. Under such conditions
the yield in any one year is cut in two to give an annual yield.
The use of the header wherever possible in harvesting dry-farm grain
also aids materially in maintaining soil fertility. By means of the
header only the heads of the grain are clipped off: the stalks are
left standing. In the fall, usually, this stubble is plowed under
and gradually decays. In the earlier dry-farm days farmers feared
that under conditions of low rainfall, the stubble or straw plowed
under would not decay, but would leave the soil in a loose dry
condition unfavorable for the growth of plants. During the last
fifteen years it has been abundantly demonstrated that if the
correct methods of dry farming are followed, so that a fair balance
of water is always found in the soil, even in the fall, the heavy,
thick header stubble may be plowed into the soil with the certainty
that it will decay and thus enrich the soil. The header stubble
contains a very large proportion of the nitrogen that the crop has
taken from the soil and more than half of the potash and phosphoric
acid. Plowing under the header stubble returns all this material to
the soil. Moreover, the bulk of the stubble is carbon taken from the
air. This decays, forming various acid substances which act on the
soil grains to set free the fertility which they contain. At the end
of the process of decay humus is formed, which is not only a
storehouse of plant-food, but effective in maintaining a good
physical condition of the soil. The introduction of the header in
dry-farming was one of the big steps in making the practice certain
and profitable.
Finally, it must be admitted that there are a great many more or
less poorly understood or unknown forces at work in all soils which
aid in the maintenance of soil-fertility. Chief among these are the
low forms of life known as bacteria. Many of these, under favorable
conditions, appear to have the power of liberating food from the
insoluble soil grains. Others have the power when settled on the
roots of leguminous or pod-bearing plants to fix nitrogen from the
air and convert it into a form suitable for the need of plants. In
recent years it has been found that other forms of bacteria, the
best known of which is azotobacter, have the power of gathering
nitrogen from the air and combining it for the plant needs without
the presence of leguminous plants. These nitrogen-gathering bacteria
utilize for their life processes the organic matter in the soil,
such as the decaying header stubble, and at the same time enrich the
soil by the addition of combined nitrogen. Now, it so happens that
these important bacteria require a soil somewhat rich in lime, well
aerated and fairly dry and warm. These conditions are all met on the
vast majority of our dry-farm soils, under the system of culture
outlined in this volume. Hall maintains that to the activity of
these bacteria must be ascribed the large quantities of nitrogen
found in many virgin soils and probably the final explanation of the
steady nitrogen supply for dry farms is to be found in the work of
the azatobacter and related forms of low life. The potash and
phosphoric acid supply can probably be maintained for ages by proper
methods of cultivation, though the phosphoric acid will become
exhausted long before the potash. The nitrogen supply, however, must
come from without. The nitrogen question will undoubtedly soon be
the one before the students of dry-farm fertility. A liberal supply
of organic matter In the soil with cultural methods favoring the
growth of the nitrogen-gathering bacteria appears at present to be
the first solution of the nitrogen question. Meanwhile, the activity
of the nitrogen-gathering bacteria, like azotobacter, is one of our
best explanations of the large presence of nitrogen in cultivated
dry-farm soils.
To summarize, the apparent increase in productivity and plant-food
content of dry-farm soils can best be explained by a consideration
of these factors: (1) the intrinsically high fertility of the arid
soils; (2) the deep feeding ground for the deep root systems of
dry-farm crops; (3) the concentration of the plant food distributed
throughout the soil by the upward movement of the natural
precipitation stored in the soil; (4) the cultural methods of
dry-farming which enable the weathering agencies to liberate freely
and vigorously the plant-food of the soil grains; (5) the small
annual crops; (6) the plowing under of the header straw, and (7) the
activity of bacteria that gather nitrogen directly from the air.
Methods of conserving soil-fertility
In view of the comparatively small annual crops that characterize
dry-farming it is not wholly impossible that the factors above
discussed, if properly applied, could liberate the latent plant-food
of the soil and gather all necessary nitrogen for the plants. Such
an equilibrium, could it once be established, would possibly
continue for long periods of time, but in the end would no doubt
lead to disaster; for, unless the very cornerstone of modern
agricultural science is unsound, there will be ultimately a
diminution of crop producing power if continuous cropping is
practiced without returning to the soil a goodly portion of the
elements of soil fertility taken from it. The real purpose of modern
agricultural researeh is to maintain or increase the productivity of
our lands; if this cannot be done, modern agriculture is essentially
a failure. Dry-farming, as the newest and probably in the future one
of the greatest divisions of modern agriculture, must from the
beginning seek and apply processes that will insure steadiness in
the productive power of its lands. Therefore, from the very
beginning dry-farmers must look towards the conservation of the
fertility of their soils.
The first and most rational method of maintaining the fertility of
the soil indefinitely is to return to the soil everything that is
taken from it. In practice this can be done only by feeding the
products of the farm to live stock and returning to the soil the
manure, both solid and liquid, produced by the animals. This brings
up at once the much discussed question of the relation between the
live stock industry and dry-farming. While it is undoubtedly true
that no system of agriculture will be wholly satisfactory to the
farmer and truly beneficial to the state, unless it is connected
definitely with the production of live stock, yet it must be
admitted that the present prevailing dry-farm conditions do not
always favor comfortable animal life. For instance, over a large
portion of the central area of the dry-farm territory the dry-farms
are at considerable distances from running or well water. In many
cases, water is hauled eight or ten miles for the supply of the men
and horses engaged in farming. Moreover, in these drier districts,
only certain crops, carefully cultivated, will yield profitably, and
the pasture and the kitchen garden are practical impossibilities
from an economic point of view. Such conditions, though profitable
dry-farming is feasible, preclude the existence of the home and the
barn on or even near the farm. When feed must be hauled many miles,
the profits of the live stock industry are materially reduced and
the dry-farmer usually prefers to grow a crop of wheat, the straw of
which may be plowed under the soil to the great advantage of the
following crop. In dry-farm districts where the rainfall is higher
or better distributed, or where the ground water is near the
surface, there should be no reason why dry-farming and live stock
should not go hand in hand. Wherever water is within reach, the
homestead is also possible. The recent development of the gasoline
motor for pumping purposes makes possible a small home garden
wherever a little water is available. The lack of water for culinary
purposes is really the problem that has stood between the joint
development of dry-farming and the live stock industry. The whole
matter, however, looks much more favorable to-day, for the efforts
of the Federal and state governments have succeeded in discovering
numerous subterranean sources of water in dry-farm districts. In
addition, the development of small irrigation systems in the
neighborhood of dry-farm districts is helping the cause of the live
stock industry. At the present time, dry-farming and the live stock
industry are rather far apart, though undoubtedly as the desert is
conquered they will become more closely associated. The question
concerning the best maintenance of soil-fertility remains the same;
and the ideal way of maintaining fertility is to return to the soil
as much as is possible of the plant-food taken from it by the crops,
which can best be accomplished by the development of the business of
keeping live stock in connection with dry-farming.
If live stock cannot be kept on a dry-farm, the most direct method
of maintaining soil-fertility is by the application of commercial
fertilizers. This practice is followed extensively in the Eastern
states and in Europe. The large areas of dry-farms and the high
prices of commercial fertilizers will make this method of manuring
impracticable on dry-farms, and it may be dismissed from thought
until such a day as conditions, especially with respect to price of
nitrates and potash, are materially changed.
Nitrogen, which is the most important plant-food that may be absent
from dry-farm soils, may be secured by the proper use of leguminous
crops. All the pod-bearing plants commonly cultivated, such as peas,
beans, vetch, clover, and lucern, are able to secure large
quantities of nitrogen from the air through the activity of bacteria
that live and grow on the roots of such plants. The leguminous crop
should be sown in the usual way, and when it is well past the
flowering stage should be plowed into the ground. Naturally, annual
legumes, such as peas and beans, should be used for this purpose.
The crop thus plowed under contains much nitrogen, which is
gradually changed into a form suitable for plant assimilation. In
addition, the acid substances produced in the decay of the plants
tend to liberate the insoluble plant-foods and the organic matter is
finally changed into humus. In order to maintain a proper supply of
nitrogen in the soil the dry-farmer will probably soon find himself
obliged to grow, every five years or oftener, a crop of legumes to
be plowed under.
Non-leguminous crops may also be plowed under for the purpose of
adding organic matter and humus to the soil, though this has little
advantage over the present method of heading the grain and plowing
under the high stubble. The header system should be generally
adopted on wheat dry-farms. On farms where corn is the chief crop,
perhaps more importance needs to be given to the supply of organic
matter and humus than on wheat farms. The occasional plowing under
of leguminous crops would he the most satisfactory method. The
persistent application of the proper cultural methods of dry-farming
will set free the most important plant-foods, and on well-cultivated
farms nitrogen is the only element likely to be absent in serious
amounts.
The rotation of crops on dry-farms is usually advocated in districts
like the Great Plains area, where the annual rainfall is over
fifteen inches and the major part of the precipitation comes in
spring and summer. The various rotations ordinarily include one or
more crops of small grains, a hoed crop like corn or potatoes, a
leguminous crop, and sometimes a fallow year. The leguminous crop is
grown to secure a fresh supply of nitrogen; the hoed crop, to enable
the air and sunshine to act thoroughly on the soil grains and to
liberate plant-food, such as potash and phosphoric acid; and the
grain crops to take up plant-food not reached by the root systems of
the other plants. The subject of proper rotation of crops has always
been a difficult one, and very little information exists on it as
practiced on dry-farms. Chilcott has done considerable work on
rotations in the Great Plains district, hut he frankly admits that
many years of trial will he necessary for the elucidation of
trustworthy principles. Some of the best rotations found by Chilcott
up to the present are:--
Corn--Wheat--Oats
Barley--Oats--Corn
Fallow--Wheat--Oats
Rosen states that rotation is very commonly practiced in the dry
sections of southern Russia, usually including an occasional Summer
fallow. As a type of an eight-year rotation practiced at the Poltava
Station, the following is given: (1) Summer tilled and manured; (2)
winter wheat; (3) hoed crop; (4) spring wheat; (5) summer fallow;
(6) winter rye; (7) buckwheat or an annual legume; (8) oats. This
rotation, it may be observed, includes the grain crop, hoed crop,
legume, and fallow every four years.
As has been stated elsewhere, any rotation in dry-farming which does
not include the summer fallow at least every third or fourth year is
likely to be dangerous In years of deficient rainfall.
This review of the question of dry-farm fertility is intended merely
as a forecast of coming developments. At the present time
soil-fertility is not giving the dry-farmers great concern, but as
in the countries of abundant rainfall the time will come when it
will be equal to that of water conservation, unless indeed the
dry-farmers heed the lessons of the past and adopt from the start
proper practices for the maintenance of the plant-food stored in the
soil. The principle explained in Chapter IX, that the amount of
water required for the production of one pound of water diminishes
as the fertility increases, shows the intimate relationship that
exists between the soil-fertility and the soil-water and the
importance of maintaining dry-farm soils at a high state of
fertility.
CHAPTER XV
IMPLEMENTS FOR DRY-FARMING
Cheap land and relatively small acre yields characterize
dry-farming. Consequently Iarger areas must be farmed for a given
return than in humid farming, and the successful pursuit of
dry-farming compels the adoption of methods that enable a man to do
the largest amount of effective work with the smallest expenditure
of energy. The careful observations made by Grace, in Utah, lead to
the belief that, under the conditions prevailing in the
intermountain country, one man with four horses and a sufficient
supply of machinery can farm 160 acres, half of which is
summer-fallowed every year; and one man may, in favorable seasons
under a carefully planned system, farm as much as 200 acres. If one
man attempts to handle a larger farm, the work is likely to be done
in so slipshod a manner that the crop yield decreases and the total
returns are no larger than if 200 acres had been well tilled.
One man with four horses would be unable to handle even 160 acres
were it not for the possession of modern machinery; and dry-farming,
more than any other system of agriculture, is dependent for its
success upon the use of proper implements of tillage. In fact, it is
very doubtful if the reclamation of the great arid and semiarid
regions of the world would have been possible a few decades ago,
before the invention and introduction of labor-saving farm
machinery. It is undoubtedly further a fact that the future of
dry-farming is closely bound up with the improvements that may be
made in farm machinery. Few of the agricultural implements on the
market to-day have been made primarily for dry-farm conditions. The
best that the dry-farmer can do is to adapt the implements on the
market to his special needs. Possibly the best field of
investigation for the experiment stations and inventive minds in the
arid region is farm mechanics as applied to the special needs of
dry-farming.
Clearing and breaking
A large portion of the dry-farm territory of the United States is
covered with sagebrush and related plants. It is always a difficult
and usually an expensive problem to clear sagebrush land, for the
shrubs are frequently from two to six feet high, correspondingly
deep-rooted, with very tough wood. When the soil is dry, it is
extremely difficult to pull out sagebrush, and of necessity much of
the clearing must be done during the dry season. Numerous devices
have been suggested and tried for the purpose of clearing sagebrush
land. One of the oldest and also one of the most effective devices
is two parallel railroad rails connected with heavy iron chains and
used as a drag over the sagebrush land. The sage is caught by the
two rails and torn out of the ground. The clearing is fairly
complete, though it is generally necessary to go over the ground two
or three times before the work is completed. Even after such
treatment a large number of sagebrush clumps, found standing over
the field, must be grubbed up with the hoe. Another and effective
device is the so-called "mankiller." This implement pulls up the
sage very successfully and drops it at certain definite intervals.
It is, however, a very dangerous implement and frequently results in
injury to the men who work it. Of recent years another device has
been tried with a great deal of success. It is made like a snow plow
of heavy railroad irons to which a number of large steel knives have
been bolted. Neither of these implements is wholly satisfactory, and
an acceptable machine for grubbing sagebrush is yet to be devised.
In view of the large expense attached to the clearing of sagebrush
land such a machine would be of great help in the advancement of
dry-farming.
Away from the sagebrush country the virgin dry-farm land is usually
covered with a more or less dense growth of grass, though true sod
is seldom found under dry-farm conditions. The ordinary breaking
plow, characterized by a long sloping moldboard, is the best known
implement for breaking all kinds of sod. (See Fig. 7a a.) Where the
sod is very light, as on the far western prairies, the more ordinary
forms of plows may be used. In still other sections, the dry-farm
land is covered with a scattered growth of trees, frequently pinion
pine and cedars, and in Arizona and New Mexico the mesquite tree and
cacti are to be removed. Such clearing has to be done in accordance
with the special needs of the locality.
Plowing
Plowing, or the turning over of the soil to a depth of from seven to
ten inches for every crop, is a fundamental operation of
dry-farming. The plow, therefore, becomes one of the most important
implements on the dry-farm. Though the plow as an agricultural
implement is of great antiquity, it is only within the last one
hundred years that it has attained its present perfection. It is a
question even to-day, in the minds of a great many students, whether
the modern plow should not be replaced by some machine even more
suitable for the proper turning and stirring of the soil. The
moldboard plow is, everything considered, the most satisfactory plow
for dry-farm purposes. A plow with a moldboard possessing a short
abrupt curvature is generally held to be the most valuable for
dry-farm purposes, since it pulverizes the soil most thoroughly, and
in dry-farming it is not so important to turn the soil over as to
crumble and loosen it thoroughly. Naturally, since the areas of
dry-farms are very large, the sulky or riding plow is the only kind
to be used. The same may be said of all other dry-farm implements.
As far as possible, they should be of the riding kind since in the
end it means economy from the resulting saving of energy.
The disk plow has recently come into prominent use throughout the
land. It consists, as is well known, of one or more large disks
which are believed to cause a smaller draft, as they cut into the
ground, than the draft due to the sliding friction upon the
moldboard. Davidson and Chase say, however, that the draft of a disk
plow is often heavier in proportion to the work done and the plow
itself is more clumsy than the moldboard plow. For ordinary dry-farm
purposes the disk plow has no advantage over the modern moldboard
plow. Many of the dry-farm soils are of a heavy clay and become very
sticky during certain seasons of the year. In such soils the disk
plow is very useful. It is also true that dry-farm soils, subjected
to the intense heat of the western sun become very hard. In the
handling of such soils the disk plow has been found to be most
useful. The common experience of dry-farmers is that when sagebrush
lands have been the first plowing can be most successfully done with
the disk plow, but that after. the first crop has been harvested,
the stubble land can be best handled with the moldboard plow. All
this, however, is yet to be subjected to further tests.
While subsoiling results in a better storage reservoir for water and
consequently makes dry-farming more secure, yet the high cost of the
practice will probably never make it popular. Subsoiling is
accomplished in two ways: either by an ordinary moldboard plow which
follows the plow in the plow furrow and thus turns the soil to a
greater depth, or by some form of the ordinary subsoil plow. In
general, the subsoil plow is simply a vertical piece of cutting
iron, down to a depth of ten to eighteen inches, at the bottom of
which is fastened a triangular piece of iron like a shovel, which,
when pulled through the ground, tends to loosen the soil to the full
depth of the plow.
The subsoil plow does not turn the soil; it simply loosens the soil
so that the air and plant roots can penetrate to greater depths.
In the choice of plows and their proper use the dryfarmer must be
guided wholly by the conditions under which he is working. It is
impossible at the present time to lay down definite laws stating
what plows are best for certain soils. The soils of the arid region
are not well enough known, nor has the relationship between the plow
and the soil been sufficiently well established. As above remarked,
here is one of the great fields for investigation for both
scientific and practical men for years to come.
Making and maintaining a soil-mulch
After the land has been so well plowed that the rains can enter
easily, the next operation of importance in dry-farming is the
making and maintaining of a soil-mulch over the ground to prevent
the evaporation of water from the soil. For this purpose some form
of harrow is most commonly used. The oldest and best-known harrow is
the ordinary smoothing harrow, which is composed of iron or steel
teeth of various shapes set in a suitable frame. (See Fig. 79.) For
dry-farm purposes the implement must be so made as to enable the
farmer to set the harrow teeth to slant backward or forward. It
frequently happens that in the spring the grain is too thick for the
moisture in the soil, and it then becomes necessary to tear out some
of the young plants. For this purpose the harrow teeth are set
straight or forward and the crop can then be thinned effectively. At
other times it may be observed in the spring that the rains and
winds have led to the formation of a crust over the soil, which must
be broken to let the plants have full freedom of growth and
development. This is accomplished by slanting the harrow teeth
backward, and the crust may then be broken without serious injury to
the plants. The smoothing harrow is a very useful implement on the
dry-farm. For following the plow, however, a more useful implement
is the disk harrow, which is a comparatively recent invention. It
consists of a series of disks which may be set at various angles
with the line of traction and thus be made to turn over the soil
while at the same time pulverizing it. The best dry-farm practice is
to plow in the fall and let the soil lie in the rough during the
winter months. In the spring the land is thoroughly disked and
reduced to a fine condition. Following this the smoothing harrow is
occasionally used to form a more perfect mulch. When seeding is to
be done immediately after plowing, the plow is followed by the disk
harrow, and that in turn is followed by the smoothing harrow. The
ground is then ready for seeding. The disk harrow is also used
extensively throughout the summer in maintaining a proper mulch. It
does its work more effectively than the ordinary smoothing harrow
and is, therefore, rapidly displacing all other forms of harrows for
the purpose of maintaining a layer of loose soil over the dry-farm.
There are several kinds of disk harrows used by dry-farmers. The
full disk is, everything considered, the most useful. The cutaway
harrow is often used in cultivating old alfalfa land; the spade disk
harrow has a very limited application in dry-farming; and the
orchard disk harrow is simply a modlfication of the full disk harrow
whereby the farmer is able to travel between the rows of trees and
so to cultivate the soil under the branches of the trees without
injuring the leaves or fruit.
One of the great difficulties in dry-farming concerns itself with
the prevention of the growth of weeds or volunteer crops. As has
been explained in previous chapters, weeds require as much water for
their growth as wheat or other useful crops. During the fallow
season, the farmer is likely to be overtaken by the weeds and lose
much of the value of the fallow by losing soil-moisture through the
growth of weeds. Under the most favorable conditions weeds are
difficult to handle. The disk harrow itself is not effective. The
smoothing harrow is of less value. There is at the present time
great need for some implement that will effectively destroy young
weeds and prevent their further growth. Attempts are being made to
invent such implements, but up to the present without great success.
Hogenson reports the finding of an implement on a western dry-farm
constructed by the farmer himself which for a number of years has
shown itself of high efficiency in keeping the dry-farm free from
weeds. Several improved modifications of this implement have been
made and tried out on the famous dry-farm district at Nephi, Utah,
and with the greatest success. Hunter reports a similar implement in
common use on the dry-farms of the Columbia Basin. Spring tooth
harrows are also used in a small way on the dry-farms.
They have no special advantage over the smoothing harrow or the disk
harrow, except in places where the attempt is made to cultivate the
soil between the rows of wheat. The curved knife tooth harrow is
scareely ever used on dry-farms. It has some value as a pulverizer,
but does not seem to have any real advantage over the ordinary disk
harrow.
Cultivators for stirring the land on which crops are growing are not
used extensively on dry-farms. Usually the spring tooth harrow is
employed for this work. In dry-farm sections, where corn is grown,
the cultivator is frequently used throughout the season. Potatoes
grown on dry-farms should be cultivated throughout the season, and
as the potato industry grows in the dry-farm territory there will be
a greater demand for suitable cultivators. The cultivators to be
used on dry-farms are all of the riding kind. They should be so
arranged that the horse walking between two rows carries a
cultivator that straddles several rows of plants and cultivates the
soil between. Disks, shovels, or spring teeth may be used on
cultivators. There is a great variety on the market, and each farmer
will have to choose such as meet most definitely his needs.
The various forms of harrows and cultivators are of the greatest
importance in the development of dry-farming. Unless a proper mulch
can be kept over the soil during the fallow season, and as far as
possible during the growing season, first-class crops cannot be
fully respected.
The roller is occasionally used in dry-farming, especially in the
uplands of the Columbia Basin. It is a somewhat dangerous implement
to use where water conservation is important, since the packing
resulting from the roller tends to draw water upward from the lower
soil layers to be evaporated into the air. Wherever the roller is
used, therefore, it should be followed immediately by a harrow. It
is valuable chiefly in the localities where the soil is very loose
and light and needs packing around the seeds to permit perfect
germination.
Subsurface packing
The subsurface packer invented by Campbell is [shown in Figure
83--not shown--ed.]. The wheels of this machine eighteen inches in
diameter, with rims one inch thick at the inner part, beveled two
and a half inches to a sharp outer edge, are placed on a shaft, five
inches apart. In practice about five hundred pounds of weight are
added.
This machine, according to Campbell, crowds a one-inch wedge into
every five inches of soil with a lateral and a downward pressure and
thus packs firmly the soil near the bottom of the plow-furrow.
Subsurface packing aims to establish full capillary connection
between the plowed upper soil and the undisturbed lower soil-layer;
to bring the moist soil in close contact with the straw or organic
litter plowed under and thus to hasten decomposition, and to provide
a firm seed bed.
The subsurface packer probably has some value where the plowed soil
containing the stubble is somewhat loose; or on soils which do not
permit of a rapid decay of stubble and other organic matter that may
be plowed under from season to season. On such soils the packing
tendency of the subsurface packer may help prevent loss of soil
water, and may also assist in furnishing a more uniform medium
through which plant roots may force their way. For all these
purposes, the disk is usually equally efficient.
Sowing
It has already been indicated in previous chapters that proper
sowing is one of the most important operations of the dry-farm,
quite comparable in importance with plowing or the maintaining of a
mulch for retaining soil-moisture. The old-fashioned method of
broadcasting has absolutely no place on a dry-farm. The success of
dry-farming depends entirely upon the control that the farmer has of
all the operations of the farm. By broadcasting, neither the
quantity of seed used nor the manner of placing the seed in the
ground can be regulated. Drill culture, therefore, introduced by
Jethro Tull two hundred years ago, which gives the farmer full
control over the process of seeding, is the only system to be used.
The numerous seed drills on the market all employ the same
principles. Their variations are few and simple. In all seed drills
the seed is forced into tubes so placed as to enable the seed to
fall into the furrows in the ground. The drills themselves are
distinguished almost wholly by the type of the furrow opener and the
covering devices which are used. The seed furrow is opened either by
a small hoe or a so-called shoe or disk. At the present time it
appears that the single disk is the coming method of opening the
seed furrow and that the other methods will gradually disappear. As
the seed is dropped into the furrow thus made it is covered by some
device at the rear of the machine. One of the oldest methods as well
as one of the most satisfactory is a series of chains dragging
behind the drill and covering the furrow quite completely. It is,
however, very desirable that the soil should be pressed carefully
around the seed so that germination may begin with the least
difficulty whenever the temperature conditions are right. Most of
the drills of the day are, therefore, provided with large light
wheels, one for each furrow, which press lightly upon the soil and
force the soil into intimate contact with the seed The weakness of
such an arrangement is that the soil along the drill furrows is left
somewhat packed, which leads to a ready escape of the soil-moisture.
Many of the drills are so arranged that press wheels may be used at
the pleasure of the farmer. The seed drill is already a very useful
implement and is rapidly being made to meet the special requirements
of the dry-farmer. Corn planters are used almost exclusively on
dry-farms where corn is the leading crop. In principle they are very
much the same as the press drills. Potatoes are also generally
planted by machinery. Wherever seeding machinery has been
constructed based upon the principles of dry-farming, it is a very
advantageous adjunct to the dry-farm.
Harvesting
The immense areas of dry-farms are harvested almost wholly by the
most modern machinery. For grain, the harvester is used almost
exclusively in the districts where the header cannot be used, but
wherever conditions permit, the header is and should be used. It has
been explained in previous chapters how valuable the tall header
stubble is when plowed under as a means of maintaining the fertility
of the soil. Besides, there is an ease in handling the header which
is not known with the harvester. There are times when the header
leads to some waste as, for instance, when the wheat is very low and
heads are missed as the machine passes over the ground. In many
sections of the dry-farm territory the climatic conditions are such
that the wheat cures perfectly while still standing. In such places
the combined harvester and thresher is used. The header cuts off the
heads of the grain, which are passed up into the thresher, and bags
filled with threshed grain are dropped along the path of the
machine, while the straw is scattered over the ground. Wherever such
a machine can be used, it has been found to be economical and
satisfactory. Of recent years corn stalks have been used to better
advantage than in the past, for not far from one half of the feeding
value of the corn crop is in the stalks, which up to a few years ago
were very largely wasted. Corn harvesters are likewise on the market
and are quite generally used. It was manifestly impossible on large
places to harvest corn by hand and large corn harvesters have,
therefore, been made for this purpose.
Steam and other motive power
Recently numerous persons have suggested that the expense of running
a dry-farm could be materially reduced by using some motive power
other than horses. Steam, gasoline, and electricity have all been
suggested. The steam traction engine is already a fairly
well-developed machine and it has been used for plowing purposes on
many dry-farms in nearly all the sections of the dry-farm territory.
Unfortunately, up to the present it has not shown itself to be very
satisfactory. First of all it is to be remembered that the
principles of dry-farming require that the topsoil be kept very
loose and spongy. The great traction engines have very wide wheels
of such tremendous weight that they press down the soil very
compactly along their path and in that way defeat one of the
important purposes of tillage. Another objection to them is that at
present their construction is such as to result in continual
breakages. While these breakages in themselves are small and
inexpensive, they mean the cessation of all farming operations
during the hour or day required for repairs. A large crew of men is
thus left more or less idle, to the serious injury of the work and
to the great expense of the owner. Undoubtedly, the traction engine
has a place in dry-farming, but it has not yet been perfected to
such a degree as to make it satisfactory. On heavy soils it is much
more useful than on light soils. When the traction engine works
satisfactorily, plowing may be done at a cost considerably lower
than when horses are employed.
In England, Germany, and other European countries some of the
difficulties connected with plowing have been overcome by using two
engines on the two opposite sides of a field. These engines move
synchronously together and, by means of large cables, plows,
harrows, or seeders, are pulled back and forth over the field. This
method seems to give good satisfaction on many large estates of the
old world. Macdonald reports that such a system is in successful
operation in the Transvaal in South Africa and is doing work there
at a very knew cost. The large initial cost of such a system will,
of course, prohibit its use except on the very large farms that are
being established in the dry-farm territory.
Gasoline engines are also being tried out, but up to date they have
not shown themselves as possessing superior advantages over the
steam engines. The two objections to them are the same as to the
steam engine: first, their great weight, which compresses in a
dangerous degree the topsoil and, secondly, the frequent breakages,
which make the operation slow and expensive.
Over a great part of the West, water power is very abundant and the
suggestion has been made that the electric energy which can be
developed by means of water power could be used in the cultural
operations of the dry-farm. With the development of the trolley car
which does not run on rails it would not seem impossible that in
favorable localities electricity could be made to serve the farmer
in the mechanical tillage of the dry-farm.
The substitution of steam and other energy for horse power is yet in
the future. Undoubtedly, it will come, but only as improvements are
made in the machines. There is here also a great field for being of
high service to the farmers who are attempting to reclaim the great
deserts of the world. As stated at the beginning of this chapter,
dry-farming would probably have been an impossibilityfifty or a
hundred years ago because of the absence of suitable machinery. The
future of dry-farming rests almost wholly, so far as its profits are
concerned, upon the development of new and more suitable machinery
for the tillage of the soil in accordance with the established
principles of dry-farming.
Finally, the recommendations made by Merrill may here be inserted. A
dry-farmer for best work should be supplied with the following
implements in addition to the necessary wagons and hand tools:--
One Plow.
One Disk.
One Smoothing Harrow.
One Drill Seeder.
One Harvester or Header.
One Mowing Machine.
CHAPTER XVI
IRRIGATION AND DRY-FARMING
Irrigation-farming and dry-farming are both systems of agriculture
devised for the reclamation of countries that ordinarily receive an
annual rainfall of twenty inches or less. Irrigation-farming cannot
of itself reclaim the arid regions of the world, for the available
water supply of arid countries when it shall have been conserved in
the best possible way cannot be made to irrigate more than one fifth
of the thirsty land. This means that under the highest possible
development of irrigation, at least in the United States, there will
be five or six acres of unirrigated or dry-farm land for every acre
of irrigated land. Irrigation development cannot possibly,
therefore, render the dry-farm movement valueless. On the other
hand, dry-farming is furthered by the development of irrigation
farming, for both these systems of agriculture are characterized by
advantages that make irrigation and dry-farming supplementary to
each other in the successful development of any arid region.
Under irrigation, smaller areas need to be cultivated for the same
crop returns, for it has been amply demonstrated that the acre
yields under proper irrigation are very much larger than the best
yields under the most careful system of dry-farming. Secondly, a
greater variety of crops may be grown on the irrigated farm than on
the dry-farm. As has already been shown in this volume, only certain
drouth resistant crops can be grown profitably upon dry-farms, and
these must be grown under the methods of extensive farming. The
longer growing crops, including trees, succulent vegetables, and a
variety of small fruits, have not as yet been made to yield
profitably under arid conditions without the artificial application
of water. Further, the irrigation-farmer is not largely dependent
upon the weather and, therefore, carries on this work with a feeling
of greater security. Of course, it is true that the dry years affect
the flow of water in the canals and that the frequent breaking of
dams and canal walls leaves the farmer helpless in the face of the
blistering heat. Yet, all in all, a greater feeling of security is
possessed by the irrigation farmer than by the dry-farmer.
Most important, however, are the temperamental differences in men
which make some desirous of giving themselves to the cultivation of
a small area of irrigated land under intensive conditions and others
to dry-farming under extensive conditions. In fact, it is being
observed in the arid region that men, because of their temperamental
differences, are gradually separating into the two classes of
irrigation-farmers and dry-farmers. The dry-farms of necessity cover
much larger areas than the irrigated farms. The land is cheaper and
the crops are smaller. The methods to be applied are those of
extensive farming. The profits on the investment also appear to be
somewhat larger. The very necessity of pitting intellect against the
fierceness of the drouth appears to have attracted many-men to the
dry-farms. Gradually the certainty of producing crops on dry-farms
from season to season is becoming established, and the essential
difference between the two kinds of farming in the arid districts
will then he the difference between intensive and extensive methods
of culture. Men will be attracted to one or other of these systems
of agriculture according to their personal inclinations.
The scarcity of water
For the development of a well-rounded commonwealth in an arid region
it is, of course, indispensable that irrigation be practiced, for
dry-farming of itself will find it difficult to build up populous
cities and to supply the great variety of crops demanded by the
modern family. In fact, one of the great problems before those
engaged in the development of dry-farming at present is the
development of homesteads in the dry-farms. A homestead is possible
only where there is a sufficient amount of free water available for
household and stock purposes. In the portion of the dry-farm
territory where the rainfall approximates twenty inches, this
problem is not so very difficult, since ground water may be reached
easily. In the drier portions, however, where the rainfall is
between ten and fifteen inches, the problem is much more important.
The conditions that bring the district under the dry-farm
designation imply a scarcity of water. On few dry-farms is water
available for the needs of the household and the barns. In the Rocky
Mountain states numerous dry-farms have been developed from seven to
fifteen miles from the nearest source of water, and the main expense
of developing these farms has been the hauling of water to the farms
to supply the needs of the men and beasts at work on them.
Naturally, it is impossible to establish homesteads on the dry-farms
unless at least a small supply of water is available; and
dry-farming will never he what it might be unless happy homes can be
established upon the farms in the arid regions that grow crops
without irrigation. To make a dry-farm homestead possible enough
water must be available, first of all, to supply the culinary needs
of the household. This of itself is not large and, as will be shown
hereafter, may in most cases be obtained. However, in order that the
family may possess proper comforts, there should be around the
homestead trees, and shrubs, and grasses, and the family garden. To
secure these things a certain amount of irrigation water is
required. It may be added that dry-farms on which such homesteads
are found as a result of the existence of a small supply of
irrigation water are much more valuable, in case of sale, than
equally good farms without the possibility of maintaining
homesteads. Moreover, the distinct value of irrigation in producing
a large acre yield makes it desirable for the farmer to use all the
water at his disposal for irrigation purposes. No available water
should be allowed to flow away unused.
Available surface water
The sources of water for dry-farms fall readily into classes:
surface waters and subterranean waters. The surface waters, wherever
they may be obtained, are generally the most profitable. The
simplest method of obtaining water in an irrigated region is from
some irrigation canal. In certain districts of the intermountain
region where the dry farms lie above the irrigation canals and the
irrigated lands below, it is comparatively easy for the farmers to
secure a small but sufficient amount of water from the canal by the
use of some pumping device that will force the water through the
pipes to the homestead. The dry-farm area that may be so supplied by
irrigation canals is, however, very limited and is not to be
considered seriously in connection with the problem.
A much more important method, especially in the mountainous
districts, is the utilization of the springs that occur in great
numbers over the whole dry-farm territory. Sometimes these springs
are very small indeed, and often, after development by tunneling
into the side of the hill, yield only a trifling flow. Yet, when
this water is piped to the homestead and allowed to accumulate in
small reservoirs or cisterns, it may be amply sufficient for the
needs of the family and the live stock, besides having a surplus for
the maintenance of the lawn, the shade trees, and the family garden.
Many dry-farmers in the intermountain country have piped water seven
or eight miles from small springs that were considered practically
worthless and thereby have formed the foundations for small village
communities.
Of perhaps equal importance with the utilization of the naturally
occurring springs is the proper conservation of the flood waters. As
has been stated before, arid conditions allow a very large loss of
the natural precipitation as run-off. The numerous gullies that
characterize so many parts of the dry-farm territory are evidences
of the number and vigor of the flood waters. The construction of
small reservoirs in proper places for the purpose of catching the
flood waters will usually enable the farmer to supply himself with
all the water needed for the homestead. Such reservoirs may already
be found in great numbers scattered over the whole western America.
As dry-farming increases their numbers will also increase.
When neither canals, nor springs, nor flood waters are available for
the supply of water, it is yet possible to obtain a limited supply
by so arranging the roof gutters on the farm buildings that all the
water that falls on the roofs is conducted through the spouts into
carefully protected cisterns or reservoirs. A house thirty by thirty
feet, the roof of which is so constructed that all that water that
falls upon it is carried into a cistern will yield annually under a
a rainfall of fifteen inches a maximum amount of water equivalent to
about 8800 gallons. Allowing for the unavoidable waste due to
evaporation, this will yield enough to supply a household and some
live stock with the necessary water. In extreme cases this has been
found to be a very satisfactory practice, though it is the one to be
resorted to only in case no other method is available.
It is indispensable that some reservoir be provided to hold the
surface water that may be obtained until the time it may be needed.
The water coming constantly from a spring in summer should be
applied to crops only at certain definite seasons of the year. The
flood waters usually come at a time when plant growth is not active
and irrigation is not needed.
The rainfall also in many districts comes most largely at seasons of
no or little plant growth. Reservoirs must, therefore, be provided
for the storing of the water until the periods when it is demanded
by crops. Cement-lined cisterns are quite common, and in many places
cement reservoirs have been found profitable. In other places the
occurrence of impervious clay has made possible the establishment
and construction of cheap reservoirs. The skillful and permanent
construction of reservoirs is a very important subject. Reservoir
building should be undertaken only after a careful study of the
prevailing conditions and under the advice of the state or
government officials having such work in charge. In general, the
first cost of small reservoirs is usually somewhat high, but in view
of their permanent service and the value of the water to the
dry-farm they pay a very handsome interest on the investment. It is
always a mistake for the dry-farmer to postpone the construction of
a reservoir for the storing of the small quantities of water that he
may possess, in order to save a little money. Perhaps the greatest
objection to the use of the reservoirs is not their relatively high
cost, but the fact that since they are usually small and the water
shallow, too large a proportion of the water, even under favorable
conditions, is lost by evaporation. It is ordinarily assumed that
one half of the water stored in small reservoirs throughout the year
is lost by direct evaporation.
Available subterranean water
Where surface waters are not readily available, the subterranean
water is of first importance. It is generally known that, underlying
the earth's surface at various depths, there is a large quantity of
free water. Those living in humid climates often overestimate the
amount of water so held in the earth's crust, and it is probably
true that those living in arid regions underestimate the quantity of
water so found. The fact of the matter seems to be that free water
is found everywhere under the earth's surface. Those familiar with
the arid West have frequently been surprised by the frequency with
which water has been found at comparatively shallow depths in the
most desert locations. Various estimates have been made as to the
quantity of underlying water. The latest calculation and perhaps the
most reliable is that made by Fuller, who, after a careful analysis
of the factors involved, concludes that the total free water held in
the earth's crust is equivalent to a uniform sheet of water over the
entire surface of the earth ninety-six feet in depth. A quantity of
water thus held would be equivalent to about one hundredth part of
the whole volume of the ocean. Even though the thickness of the
water sheet under arid soils is only half this figure there is an
amount, if it could be reached, that would make possible the
establishment of homesteads over the whole dry-farm territory. One
of the main efforts of the day is the determination of the
occurrence of the subterranean waters in the dry-farm territory.
Ordinary dug wells frequently reach water at comparatively shallow
depths. Over the cultivated Utah deserts water is often found at a
depth of twenty-five or thirty feet, though many wells dug to a
depth of one hundred and seventy-five and two hundred feet have
failed to reach water. It may be remarked in this connection that
even where the distance to the water is small, the piped well has
been found to be superior to the dug well. Usually, water is
obtained in the dry-farm territory by driving pipes to comparatively
great depths, ranging from one hundred feet to over one thousand
feet. At such depths water is nearly always found. Often the
geological conditions are such as to force the water up above the
surface as artesian wells, though more often the pressure is simply
sufficient to bring the water within easy pumping distance of the
surface. In connection with this subject it must be said that many
of the subterranean waters of the dry-farm territory are of a saline
character. The amount of substances held in solution varies largely,
but frequently is far above the limits of safety for the use of man
or beast or plants. The dry-farmer who secures a well of this type
should, therefore, be careful to have a proper examination made of
the constituents of the water before ordinary use is made of it.
Now, as has been said, the utilization of the subterranean waters of
the land is one of the living problems of dry-farming. The tracing
out of this layer of water is very difficult to accomplish and
cannot be done by individuals. It is a work that properly belongs to
the state and national government. The state of Utah, which was the
pioneer in appropriating money for dry-farm experiments, also led
the way in appropriating money for the securing of water for the
dry-farms from subterranean sources. The world has been progressing
in Utah since 1905, and water has been secured in the most
unpromising localities. The most remarkable instance is perhaps the
finding of water at a depth of about five hundred and fifty feet in
the unusually dry Dog Valley located some fifteen miles west of
Nephi.
Pumping water
The use of small quantities of water on the dry-farms carries with
it, in most cases, the use of small pumping plants to store and to
distribute the water properly. Especially, whenever subterranean
sources of water are used and the water pressure is not sufficient
to throw the water above the ground, pumping must be resorted to.
The pumping of water for agricultural purposes is not at all new.
According to Fortier, two hundred thousand acres of land are
irrigated with water pumped from driven wells in the state of
California alone. Seven hundred and fifty thousand acres are
irrigated by pumping in the United States, and Mead states that
there are thirteen million acres of land in India which are
irrigated by water pumped from subterranean sources. The dry-farmer
has a choice among several sources of power for the operation of his
pumping plant. In localities where winds are frequent and of
sufficient strength windmills furnish cheap and effective power,
especially where the lift is not very great. The gasoline engine is
in a state of considerable perfection and may be used economically
where the price of gasoline is reasonable. Engines using crude oil
may be most desirable in the localities where oil wells have been
found. As the manufacture of alcohol from the waste products of the
farms becomes established, the alcohol-burning engine could become a
very important one. Over nearly the whole of the dry-farm territory
coal is found in large quantities, and the steam engine fed by coal
is an important factor in the pumping of water for irrigation
purposes. Further, in the mountainous part of the dry-farm territory
water Power is very abundant. Only the smallest fraction of it has
as yet been harnessed for the generation of the electric current. As
electric generation increases, it should be comparatively easy for
the farmer to secure sufficient electric power to run the pump. This
has already become an established practice in districts where
electric power is available.
During the last few years considerable work has been done to
determine the feasibility of raising water for irrigation by
pumping. Fortier reports that successful results have been obtained
in Colorado, Wyoming, and Montana. He declares that a good type of
windmill located in a district where the average wind movement is
ten miles per hour can lift enough water twenty feet to irrigate
five acres of land. Wherever the water is near the surface this
should be easy of accomplishment. Vernon, Lovett, and Scott, who
worked under New Mexico conditions, have reported that crops can be
produced profitably by the use of water raised to the surface for
irrigation. Fleming and Stoneking, who conducted very careful
experiments on the subject in New Mexico, found that the cost of
raising through one foot a quantity of water corresponding to a
depth of one foot over one acre of land varied from a cent and an
eighth to nearly twenty-nine cents, with an average of a little more
than ten cents. This means that the cost of raising enough water to
cover one acre to a depth of one foot through a distance of forty
feet would average $4.36. This includes not only the cost of the
fuel and supervision of the pump but the actual deterioration of the
plant. Smith investigated the same problem under Arizona conditions
and found that it cost approximately seventeen cents to raise one
acre foot of water to a height of one foot. A very elaborate
investigation of this nature was conducted in California by Le Conte
and Tait. They studied a large number of pumping plants in actual
operation under California conditions, and determined that the total
cost of raising one acre foot of water one foot was, for gasoline
power, four cents and upward; for electric power, seven to sixteen
cents, and for steam, four cents and upward. Mead has reported
observations on seventy-two windmills near Garden City, Kansas,
which irrigated from one fourth to seven acres each at a cost of
seventy-five cents to $6 per acre. All in all, these results justify
the belief that water may be raised profitably by pumping for the
purpose of irrigating crops. When the very great value of a little
water on a dry-farm is considered, the figures here given do not
seem at all excessive. It must be remarked again that a reservoir of
some sort is practically indispensable in connection with a pumping
plant if the irrigation water is to be used in the best way.
The use of small quantities of water in irrigation
Now, it is undoubtedly true that the acre cost of water on
dry-farms, where pumping plants or similar devices must be used with
expensive reservoirs, is much higher than when water is obtained
from gravity canals. It is, therefore, important that the costly
water so obtained be used in the most economical manner. This is
doubly important in view of the fact that the water supply obtained
on dry-farms is always small and insufficient for all that the
farmer would like to do. Indeed, the profit in storing and pumping
water rests largely upon the economical application of water to
crops. This necessitates the statement of one of the first
principles of scientific irrigation practices, namely, that the
yield of a crop under irrigation is not proportional to the amount
of water applied in the form of irrigation water. In other words,
the water stored in the soil by the natural precipitation and the
water that falls during the spring and summer can either mature a
small crop or bring a crop near maturity. A small amount of water
added in the form of irrigation water at the right time will usually
complete the work and produce a well-matured crop of large yield.
Irrigation should only be supplemented to the natural precipitation.
As more irrigation water is added, the increase in yield becomes
smaller in proportion to the amount of water employed. This is
clearly shown by the following table, which is taken from some of
the irrigation experiments carried on at the Utah Station:--
Effect of Varying Irrigations on Crop Yields Per Acre
Depth of Water Wheat Corn Alfalfa Potatoes Sugar Beets
Applied (Inches) (Bushels) (Bushels) (Pounds) (Bushels) (Tons)
5.0 40 194 25
7.5 41 65
10.0 41 80 213 26
15.0 46 78 253 27
25.0 49 77 10,056 258
35.0 55 9,142 291 26
50 60 84 13,061
The soil was a typical arid soil of great depth and had been so
cultivated as to contain a large quantity of the natural
precipitation. The first five inches of water added to the
precipitation already stored in the soil produced forty bushels of
wheat. Doubling this amount of irrigation water produced only
forty-one bushels of wheat. Even with an irrigation of fifty inches,
or ten times that which produced forty bushels, only sixty bushels
of wheat, or an increase of one half, were produced. A similar
variation may be observed in the case of the other crops. The first
lesson to be drawn from this important principle of irrigation is
that if the soil be so treated as to contain at planting time the
largest proportion of the natural precipitation,--that is, if the
ordinary methods of dry-farming be employed,--crops will be produced
with a very small amount of irrigation water. Secondly, it follows
that it would be a great deal better for the farmer who raises
wheat, for instance, to cover ten acres of land with water to a
depth of five inches than to cover one acre to a depth of fifty
inches, for in the former case four hundred bushels and in the
second sixty bushels of wheat would be produced. The farmer who
desires to utilize in the most economical manner the small amount of
water at his disposal must prepare the land according to dry-farm
methods and then must spread the water at his disposal over a larger
area of land. The land must be plowed in the fall if the conditions
permit, and fallowing should be practiced wherever possible. If the
farmer does not wish to fallow his family garden he can achieve
equally good results by planting the rows twice as far apart as is
ordinarily the case and by bringing the irrigation furrows near the
rows of plants. Then, to make the best use of the water, he must
carefully cover the irrigation furrow with dry dirt immediately
after the water has been applied and keep the whole surface well
stirred so that evaporation will be reduced to a minimum. The
beginning of irrigation wisdom is always the storage of the natural
precipitation. When that is done correctly, it is really remarkable
how far a small amount of irrigation water may be made to go.
Under conditions of water scarcity it is often found profitable to
carry water to the garden in cement or iron pipes so that no water
may be lost by seepage or evaporation during the conveyance of the
water from the reservoir to the garden. It is also often desirable
to convey water to plants through pipes laid under the ground,
perforated at various intervals to allow the water to escape and
soak into the soil in the neighborhood of the plant roots. All such
refined methods of irrigation should be carefully investigated by
the who wants the largest results from his limited water supply.
Though such methods may seem cumbersome and expensive at first, yet
they will be found, if properly arranged, to be almost automatic in
their operation and also very profitable.
Forbes has reported a most interesting experiment dealing with the
economical use of a small water supply under the long season and
intense water dissipating conditions of Arizona. The source of
supply was a well, 90 feet deep. A 3 by 14-inch pump cylinder
operated by a 12-foot geared windmill lifted the water into a
5000-gallon storage reservoir standing on a support 18 feet high.
The water was conveyed from this reservoir through black iron pipes
buried 1 or 2 feet from the trees to be watered. Small holes in the
pipe 332 inch in diameter allowed the water to escape at desirable
intervals. This irrigation plant was under expert observation for
considerable time, and it was found to furnish sufficient water for
domestic use for one household, and irrigated in addition 61 olive
trees, 2 cottonwoods, 8 pepper trees, 1 date palm, 19 pomegranates,
4 grapevines, 1 fig tree, 9 eucalyptus trees, 1 ash, and 13
miscellancous, making a total of 87 useful trees, mainly
fruit-bearing, and 32 vines and bushes. (See Fig. 95.) If such a
result can be obtained with a windmill and with water ninety feet
below the surface under the arid conditions of Arizona, there should
be little difficulty in securing sufficient water over the larger
portions of the dry-farm territory to make possible beautiful
homesteads.
The dry-farmer should carefully avoid the temptation to decry
irrigation practices. Irrigation and dry-farming of necessity must
go hand in hand in the development of the great arid regions of the
world. Neither can well stand alone in the building of great
commonwealths on the deserts of the earth.
CHAPTER XVII
THE HISTORY OF DRY-FARMING
The great nations of antiquity lived and prospered in arid and
semiarid countries. In the more or less rainless regions of China,
Mesopotamia, Palestine, Egypt, Mexico, and Peru, the greatest cities
and the mightiest peoples flourished in ancient days. Of the great
civilizations of history only that of Europe has rooted in a humid
climate. As Hilgard has suggested, history teaches that a high
civilization goes hand in hand with a soil that thirsts for water.
To-day, current events point to the arid and semiarid regions as the
chief dependence of our modern civilization.
In view of these facts it may be inferred that dry-farming is an
ancient practice. It is improbable that intelligent men and women
could live in Mesopotamia, for example, for thousands of years
without discovering methods whereby the fertile soils could be made
to produce crops in a small degree at least without irrigation.
True, the low development of implements for soil culture makes it
fairly certain that dry-farming in those days was practiced only
with infinite labor and patience; and that the great ancient nations
found it much easier to construct great irrigation systems which
would make crops certain with a minimum of soil tillage, than so
thoroughly to till the soil with imperfect implements as to produce
certain yields without irrigation. Thus is explained the fact that
the historians of antiquity speak at length of the wonderful
irrigation systems, but refer to other forms of agriculture in a
most casual manner. While the absence of agricultural machinery
makes it very doubtful whether dry-farming was practiced extensively
in olden days, yet there can be little doubt of the high antiquity
of the practice.
Kearney quotes Tunis as an example of the possible extent of
dry-farming in early historical days. Tunis is under an average
rainfall of about nine inches, and there are no evidences of
irrigation having been practiced there, yet at El Djem are the ruins
of an amphitheater large enough to accommodate sixty thousand
persons, and in an area of one hundred square miles there were
fifteen towns and forty-five villages. The country, therefore, must
have been densely populated. In the seventh century, according to
the Roman records, there were two million five hundred thousand
acres of olive trees growing in Tunis and cultivated without
irrigation. That these stupendous groves yielded well is indicated
by the statement that, under the Caesar's Tunis was taxed three
hundred thousand gallons of olive oil annually. The production of
oil was so great that from one town it was piped to the nearest
shipping port. This historical fact is borne out by the present
revival of olive culture in Tunis, mentioned in Chapter XII.
Moreover, many of the primitive peoples of to-day, the Chinese,
Hindus, Mexicans, and the American Indians, are cultivating large
areas of land by dry-farm methods, often highly perfected, which
have been developed generations ago, and have been handed down to
the present day. Martin relates that the Tarahumari Indians of
northern Chihuahua, who are among the most thriving aboriginal
tribes of northern Mexico, till the soil by dry-farm methods and
succeed in raising annually large quantities of corn and other
crops. A crop failure among them is very uncommon. The early
American explorers, especially the Catholic fathers, found
occasional tribes in various parts of America cultivating the soil
successfully without irrigation. All this points to the high
antiquity of agriculture without irrigation in arid and semiarid
countries.
Modern dry-farming in the United States
The honor of having originated modern dry-farming belongs to the
people of Utah. On July 24th, 1847, Brigham Young with his band of
pioneers entered Great Salt Lake Valley, and on that day ground was
plowed, potatoes planted, and a tiny stream of water led from City
Creek to cover this first farm. The early endeavors of the Utah
pioneers were devoted almost wholly to the construction of
irrigation systems. The parched desert ground appeared so different
from the moist soils of Illinois and Iowa, which the pioneers had
cultivated, as to make it seem impossible to produce crops without
irrigation. Still, as time wore on, inquiring minds considered the
possibility of growing crops without irrigation; and occasionally
when a farmer was deprived of his supply of irrigation water through
the breaking of a canal or reservoir it was noticed by the community
that in spite of the intense heat the plants grew and produced small
yields.
Gradually the conviction grew upon the Utah pioneers that farming
without irrigation was not an impossibility; but the small
population were kept so busy with their small irrigated farms that
no serious attempts at dry-farming were made during the first seven
or eight years. The publications of those days indicate that
dry-farming must have been practiced occasionally as early as 1854
or 1855.
About 1863 the first dry-farm experiment of any consequence occurred
in Utah. A number of emigrants of Scandinavian descent had settled
in what is now known as Bear River City, and had turned upon their
farms the alkali water of Malad Creek, and naturally the crops
failed. In desperation the starving settlers plowed up the sagebrush
land, planted grain, and awaited results. To their surprise, fair
yields of grain were obtained, and since that day dry-farming has
been an established practice in that portion of the Great Salt Lake
Valley. A year or two later, Christopher Layton, a pioneer who
helped to build both Utah and Arizona, plowed up land on the famous
Sand Ridge between Salt Lake City and Ogden and demonstrated that
dry-farm wheat could be grown successfully on the deep sandy soil
which the pioneers had held to be worthless for agricultural
purposes. Since that day the Sand Ridge has been famous as a
dry-farm district, and Major J. W. Powell, who saw the ripened
fields of grain in the hot dry sand, was moved upon to make special
mention of them in his volume on the "Arid Lands of Utah," published
in 1879.
About this time, perhaps a year or two later, Joshua Salisbury and
George L. Farrell began dry-farm experiments in the famous Cache
Valley, one hundred miles north of Salt Lake City. After some years
of experimentation, with numerous failures these and other pioneers
established the practice of dry-farming in Cache Valley, which at
present is one of the most famous dry-farm sections in the United
States. In Tooele County, Just south of Salt Lake City, dry-farming
was practiced in 1877--how much earlier is not known. In the
northern Utah counties dry-farming assumed proportions of
consequence only in the later '70's and early '80's. During the
'80's it became a thoroughly established and extensive business
practice in the northern part of the state.
California, which was settled soon after Utah, began dry-farm
experiments a little later than Utah. The available information
indicates that the first farming without irrigation in California
began in the districts of somewhat high precipitation. As the
population increased, the practice was pushed away from the
mountains towards the regions of more limited rainfall. According to
Hilgard, successful dry-farming on an extensive scale has been
practiced in California since about 1868. Olin reports that
moisture-saving methods were used on the Californian farms as early
as 1861. Certainly, California was a close second in originating
dry-farming.
The Columbia Basin was settled by Mareus Whitman near Walla Walla in
1836, but farming did not gain much headway until the railroad
pushed through the great Northwest about 1880. Those familiar with
the history of the state of Washington declare that dry-farming was
in successful operation in isolated districts in the late '70's. By
1890 it was a well-established practice, but received a serious
setback by the financial panic of 1892-1893. Really successful and
extensive dry-farming in the Columbia Basin began about 1897. The
practice of summer fallow had begun a year or two before. It is
interesting to note that both in California and Washington there are
districts in which dry-farming has been practiced successfully under
a precipitation of about ten inches whereas in Utah the limit has
been more nearly twelve inches.
In the Great Plains area the history of dry-farming Is hopelessly
lost in the greater history of the development of the eastern and
more humid parts of that section of the country. The great influx of
settlers on the western slope of the Great Plains area occurred in
the early '80's and overflowed into eastern Colorado and Wyoming a
few years later. The settlers of this region brought with them the
methods of humid agriculture and because of the relatively high
precipitation were not forced into the careful methods of moisture
conservation that had been forced upon Utah, California, and the
Columbia Basin. Consequently, more failures in dry-farming are
reported from those early days in the Great Plains area than from
the drier sections of the far West Dry-farming was practiced very
successfully in the Great Plains area during the later '80's.
According to Payne, the crops of 1889 were very good; in 1890, less
so; in 1891, better; in 1892 such immense crops were raised that the
settlers spoke of the section as God's country; in 1893, there was a
partial failure, and in 1894 the famous complete failure, which was
followed in 1895 by a partial failure. Since that time fair crops
have been produced annually. The dry years of 1893-1895 drove most
of the discouraged settlers back to humid sections and delayed, by
many years, the settlement and development of the western side of
the Great Plains area. That these failures and discouragements were
due almost entirely to improper methods of soil culture is very
evident to the present day student of dry-farming. In fact, from the
very heart of the section which was abandoned in 1893-1895 come
reliable records, dating back to 1886, which show successful crop
production every year. The famous Indian Head experimental farm of
Saskatchewan, at the north end of the Great Plains area, has an
unbroken record of good crop yields from 1888, and the early '90's
were quite as dry there as farther south. However, in spite of the
vicissitudes of the section, dry-farming has taken a firm hold upon
the Great Plains area and is now a well-established practice.
The curious thing about the development of dry-farming in Utah,
California, Washington, and the Great Plains is that these four
sections appear to have originated dry-farming independently of each
other. True, there was considerable communication from 1849 onward
between Utah and California, and there is a possibility that some of
the many Utah settlers who located in California brought with them
accounts of the methods of dry-farming as practiced in Utah. This,
however, cannot be authenticated. It is very unlikely that the
farmers of Washington learned dry-farming from their California or
Utah neighbors, for until 1880 communication between Washington and
the colonies in California and Utah was very difficult, though, of
course, there was always the possibility of accounts of agricultural
methods being carried from place to place by the moving emigrants.
It is fairly certain that the Great Plains area did not draw upon
the far West for dry-farm methods. The climatic conditions are
considerably different and the Great Plains people always considered
themselves as living in a very humid country as compared with the
states of the far West. It may be concluded, therefore, that there
were four independent pioneers in dry-farming in United States.
Moreover, hundreds, probably thousands, of individual farmers over
the semiarid region have practiced dry-farming thirty to fifty years
with methods by themselves.
Although these different dry-farm sections were developed
independently, yet the methods which they have finally adopted are
practically identical and include deep plowing, unless the subsoil
is very lifeless; fall plowing; the planting of fall grain wherever
fall plowing is possible; and clean summer fallowing. About 1895 the
word began to pass from mouth to mouth that probably nearly all the
lands in the great arid and semiarid sections of the United States
could be made to produce profitable crops without irrigation. At
first it was merely a whisper; then it was talked aloud, and before
long became the great topic of conversation among the thousands who
love the West and wish for its development. Soon it became a
National subject of discussion. Immediately after the close of the
nineteenth century the new awakening had been accomplished and
dry-farming was moving onward to conquer the waste places of the
earth.
H. W. Campbell
The history of the new awakening in dry-farming cannot well be
written without a brief account of the work of H. W. Campbell who,
in the public mind, has become intimately identified with the
dry-farm movement. H. W. Campbell came from Vermont to northern
South Dakota in 1879, where in 1882 he harvested a banner
crop,--twelve thousand bushels of wheat from three hundred acres. In
1883, on the same farm he failed completely. This experience led him
to a study of the conditions under which wheat and other crops may
be produced in the Great Plains area. A natural love for
investigation and a dogged persistence have led him to give his life
to a study of the agricultural problems of the Great Plains area. He
admits that his direct inspiration came from the work of Jethro
Tull, who labored two hundred years ago, and his disciples. He
conceived early the idea that if the soil were packed near the
bottom of the plow furrow, the moisture would be retained better and
greater crop certainty would result. For this purpose the first
subsurface packer was invented in 1885. Later, about 1895, when his
ideas had crystallized into theories, he appeared as the publisher
of Campbell's "Soil Culture and Farm Journal." One page of each
issue was devoted to a succinct statement of the "Campbell Method."
It was in 1898 that the doctrine of summer tillage was begun to be
investigated by him.
In view of the crop failures of the early '90's and the gradual
dry-farm awakening of the later '90's, Campbell's work was received
with much interest. He soon became identified with the efforts of
the railroads to maintain demonstration farms for the benefit of
intending settlers. While Campbell has long been in the service of
the railroads of the semiarid region, yet it should be said in all
fairness that the railroads and Mr. Campbell have had for their
primary object the determination of methods whereby the farmers
could be made sure of successful crops.
Mr. Campbell's doctrines of soil culture, based on his accumulated
experience, are presented in Campbell's "Soil Culture Manual," the
first edition of which appeared about 1904 and the latest edition,
considerably extended, was published in 1907. The 1907 manual is the
latest official word by Mr. Campbell on the principles and methods
of the "Campbell system." The essential features of the system may
be summarized as follows: The storage of water in the soil is
imperative for the production of crops in dry years. This may be
accomplished by proper tillage. Disk the land immediately after
harvest; follow as soon as possible with the plow; follow the plow
with the subsurface packer; and follow the packer with the smoothing
harrow. Disk the land again as early as possible in the spring and
stir the soil deeply and carefully after every rain. Sow thinly in
the fall with a drill. If the grain is too thick in the spring,
harrow it out. To make sure of a crop, the land should be "summer
tilled," which means that clean summer fallow should be practiced
every other year, or as often as may be necessary.
These methods, with the exception of the subsurface packing, are
sound and in harmony with the experience of the great dry-farm
sections and with the principles that are being developed by
scientific investigation. The "Campbell system" as it stands to-day
is not the system first advocated by him. For instance, in the
beginning of his work he advocated sowing grain in April and in rows
so far apart that spring tooth harrows could be used for cultivating
between the rows. This method, though successful in conserving
moisture, is too expensive and is therefore superseded by the
present methods. Moreover, his farm paper of 1896, containing a full
statement of the "Campbell method," makes absolutely no mention of
"summer tillage," which is now the very keystone of the system.
These and other facts make it evident that Mr. Campbell has very
properly modified his methods to harmonize with the best experience,
but also invalidate the claim that he is the author of the dry-farm
system. A weakness of the "Campbell system" is the continual
insistence upon the use of the subsurface packer. As has already
been shown, subsurface packing is of questionable value for
successful crop production, and if valuable, the results may be much
more easily and successfully obtained by the use of the disk and
harrow and other similar implements now on the market. Perhaps the
one great weakness in the work of Campbell is that he has not
explained the principles underlying his practices. His publications
only hint at the reasons. H. W. Campbell, however, has done much to
popularize the subject of dry-farming and to prepare the way for
others. His persistence in his work of gathering facts, writing, and
speaking has done much to awaken interest in dry-farming. He has
been as "a voice in the wilderness" who has done much to make
possible the later and more systematic study of dry-farming. High
honor should be shown him for his faith in the semiarid region, for
his keen observation, and his persistence in the face of
difficulties. He is justly entitled to be ranked as one of the great
workers in behalf of the reclamation, without irrigation, of the
rainless sections of the world.
The experiment stations
The brave pioneers who fought the relentless dryness of the Great
American Desert from the memorable entrance of the Mormon pioneers
into the valley of the Great Salt Lake in 1847 were not the only
ones engaged in preparing the way for the present day of great
agricultural endeavor. Other, though perhaps more indirect, forces
were also at work for the future development of the semiarid
section. The Morrill Bill of 1862, making it possible for
agricultural colleges to be created in the various states and
territories, indicated the beginning of a public feeling that modern
methods should be applied to the work of the farm. The passage in
1887 of the Hatch Act, creating agricultural experiment stations in
all of the states and territories, finally initiated a new
agricultural era in the United States. With the passage of this
bill, stations for the application of modern science to crop
production were for the first time authorized in the regions of
limited rainfall, with the exception of the station connected with
the University of California, where Hilgard from 1872 had been
laboring in the face of great difficulties upon the agricultural
problems of the state of California. During the first few years of
their existence, the stations were busy finding men and problems.
The problems nearest at hand were those that had been attacked by
the older stations founded under an abundant rainfall and which
could not be of vital interest to arid countries. The western
stations soon began to attack their more immediate problems, and it
was not long before the question of producing crops without
irrigation on the great unirrigated stretches of the West was
discussed among the station staffs and plans were projected for a
study of the methods of conquering the desert.
The Colorado Station was the first to declare its good intentions in
the matter of dry-farming, by inaugurating definite experiments. By
the action of the State Legislature of 1893, during the time of the
great drouth, a substation was established at Cheyenne Wells, near
the west border of the state and within the foothills of the Great
Plains area. From the summer of 1894 until 1900 experiments were
conducted on this farm. The experiments were not based upon any
definite theory of reclamation, and consequently the work consisted
largely of the comparison of varieties, when soil treatment was the
all-important problem to be investigated. True in 1898, a trial of
the "Campbell method" was undertaken. By the time this Station had
passed its pioneer period and was ready to enter upon more
systematic investigation, it was closed. Bulletin 59 of the Colorado
Station, published in 1900 by J. E. Payne, gives a summary of
observations made on the Cheyenne Wells substation during seven
years. This bulletin is the first to deal primarily with the
experimental work relating to dry-farming in the Great Plains area.
It does not propose or outline any system of reclamation. Several
later publications of the Colorado Station deal with the problems
peculiar to the Great Plains.
At the Utah Station the possible conquest of the sagebrush deserts
of the Great Basin without irrigation was a topic of common
conversation during the years 1894 and 1895. In 1896 plans were
presented for experiments on the principles of dry-farming. Four
years later these plans were carried into effect. In the summer of
1901, the author and L. A. Merrill investigated carefully the
practices of the dry-farms of the state. On the basis of these
observations and by the use of the established principles of the
relation of water to soils and plants, a theory of dry-farming was
worked out which was published in Bulletin 75 of the Utah Station in
January, 1902. This is probably the first systematic presentation of
the principles of dry-farming. A year later the Legislature of the
state of Utah made provision for the establishment and maintenance
of six experimental dry-farms to investigate in different parts of
the state the possibility of dry-farming and the principles
underlying the art. These stations, which are still maintained, have
done much to stimulate the growth of dry-farming in Utah. The credit
of first undertaking and maintaining systematic experimental work in
behalf of dry-farming should be assigned to the state of Utah. Since
dry-farm experiments began in Utah in 1901, the subject has been a
leading one in the Station and the College. A large number of men
trained at the Utah Station and College have gone out as
investigators of dry-farming under state and Federal direction.
The other experiment stations in the arid and semi-arid region were
not slow to take up the work for their respective states. Fortier
and Linfield, who had spent a number of years in Utah and had become
somewhat familiar with the dry-farm practices of that state,
initiated dry-farm investigations in Montana, which have been
prosecuted with great vigor since that time. Vernon, under the
direction of Foster, who had spent four years in Utah as Director of
the Utah Station, initiated the work in New Mexico. In Wyoming the
experimental study of dry-farm lands began by the private enterprise
of H. B. Henderson and his associates. Later V. T. Cooke was placed
in charge of the work under state auspices, and the demonstration of
the feasibility of dry-farming in Wyoming has been going on since
about 1907. Idaho has also recently undertaken dry-farm
investigations. Nevada, once looked upon as the only state in the
Union incapable of producing crops without irrigation, is
demonstrating by means of state appropriations that large areas
there are suitable for dry-farming. In Arizona, small tracts in this
sun-baked state are shown to be suitable for dry-farm lands. The
Washington Station is investigating the problems of dry-farming
peculiar to the Columbia Basin, and the staff of the Oregon Station
is carrying on similar work. In Nebraska, some very important
experiments dry-farming are being conducted. In North Dakota there
were in 1910 twenty-one dry-farm demonstration farms. In South
Dakota, Kansas, and Texas, provisions are similarly made for
dry-farm investigations. In fact, up and down the Great Plains area
there are stations maintained by the state or Federal government for
the purpose of determining the methods under which crops can be
produced without irrigation.
At the head of the Great Plains area at Saskatchewan one of the
oldest dry-farm stations in America is located (since 1888). In
Russia several stations are devoted very largely to the problems of
dry land agriculture. To be especially mentioned for the excellence
of the work done are the stations at Odessa, Cherson, and Poltava.
This last-named Station has been established since 1886.
In connection with the work done by the experiment stations should
be mentioned the assistance given by the railroads. Many of the
railroads owning land along their respective lines are greatly
benefited in the selling of these lands by a knowledge of the
methods whereby the lands may be made productive. However, the
railroads depend chiefly for their success upon the increased
prosperity of the population along their lines and for the purpose
of assisting the settlers in the arid West considerable sums have
been expended by the railroads in cooperation with the stations for
the gathering of information of value in the reclamation of arid
lands without irrigation.
It is through the efforts of the experiment stations that the
knowledge of the day has been reduced to a science of dry-farming.
Every student of the subject admits that much is yet to be learned
before the last word has been said concerning the methods of
dry-farming in reclaiming the waste places of the earth. The future
of dry-farming rests almost wholly upon the energy and intelligence
with which the experiment stations in this and other countries of
the world shall attack the special problems connected with this
branch of agriculture.
The United States Department of Agriculture
The Commissioner of Agriculture of the United States was given a
secretaryship in the President's Cabinet in 1889. With this added
dignity, new life was given to the department. Under the direction
of J. Sterling Morton preliminary work of great importance was done.
Upon the appointment of James Wilson as Secretary of Agriculture,
the department fairly leaped into a fullness of organization for the
investigation of the agricultural problems of the country. From the
beginning of its new growth the United States Department of
Agriculture has given some thought to the special problems of the
semiarid region, especially that part within the Great Plains.
Little consideration was at first given to the far West. The first
method adopted to assist the farmers of the plains was to find
plants with drouth resistant properties. For that purpose explorers
were sent over the earth, who returned with great numbers of new
plants or varieties of old plants, some of which, such as the durum
wheats, have shown themselves of great value in American
agriculture. The Bureaus of Plant Industry, Soils, Weather, and
Chemistry have all from the first given considerable attention to
the problems of the arid region. The Weather Bureau, long
established and with perfected methods, has been invaluable in
guiding investigators into regions where experiments could be
undertaken with some hope of success. The Department of Agriculture
was somewhat slow, however, in recognizing dry-farming as a system
of agriculture requiring special investigation. The final
recognition of the subject came with the appointment, in 1905, of
Chilcott as expert in charge of dry-land investigations. At the
present time an office of dry-land investigations has been
established under the Bureau of Plant Industry, which cooperates
with a number of other divisions of the Bureau in the investigation
of the conditions and methods of dry-farming. A large number of
stations are maintained by the Department over the arid and semiarid
area for the purpose of studying special problems, many of which are
maintained in connection with the state experiment stations. Nearly
all the departmental experts engaged in dry-farm investigation have
been drawn from the service of the state stations and in these
stations had received their special training for their work. The
United States Department of Agriculture has chosen to adopt a strong
conservatism in the matter of dry-farming. It may be wise for the
Department, as the official head of the agricultural interests of
the country, to use extreme care in advocating the settlement of a
region in which, in the past, farmers had failed to make a living,
yet this conservatism has tended to hinder the advancement of
dry-farming and has placed the departmental investigations of
dry-farming in point of time behind the pioneer investigations of
the subject.
The Dry-farming Congress
As the great dry-farm wave swept over the country, the need was felt
on the part of experts and laymen of some means whereby dry-farm
ideas from all parts of the country could be exchanged. Private
individuals by the thousands and numerous state and governmental
stations were working separately and seldom had a chance of
comparing notes and discussing problems. A need was felt for some
central dry-farm organization. An attempt to fill this need was made
by the people of Denver, Colorado, when Governor Jesse F. McDonald
of Colorado issued a call for the first Dry-farming Congress to be
held in Denver, January 24, 25, and 26, 1907. These dates were those
of the annual stock show which had become a permanent institution of
Denver and, in fact, some of those who were instrumental in the
calling of the Dry-farming Congress thought that it was a good
scheme to bring more people to the stock show. To the surprise of
many the Dry-farming Congress became the leading feature of the
week. Representatives were present from practically all the states
interested in dry-farming and from some of the humid states. Utah,
the pioneer dry-farm state, was represented by a delegation second
in size only to that of Colorado, where the Congress was held. The
call for this Congress was inspired, in part at least, by real
estate men, who saw in the dry-farm movement an opportunity to
relieve themselves of large areas of cheap land at fairly good
prices. The Congress proved, however, to be a businesslike meeting
which took hold of the questions in earnest, and from the very first
made it clear that the real estate agent was not a welcome member
unless he came with perfectly honest methods.
The second Dry-farming Congress was held January 22 to 25, 1908, in
Salt Lake City, Utah, under the presidency of Fisher Harris. It was
even better attended than the first. The proceedings show that it
was a Congress at which the dry-farm experts of the country stated
their findings. A large exhibit of dry-farm products was held in
connection with this Congress, where ocular demonstrations of the
possibility of dry-farming were given any doubting Thomas.
The third Dry-farming Congress was held February 23 to 25, 1909, at
Cheyenne, Wyoming, under the presidency of Governor W. W. Brooks of
Wyoming. An unusually severe snowstorm preceded the Congress, which
prevented many from attending, yet the number present exceeded that
at any of the preceding Congresses. This Congress was made notable
by the number of foreign delegates who had been sent by their
respective countries to investigate the methods pursued in America
for the reclamation of the arid districts. Among these delegates
were representatives from Canada, Australia, The Transvaal, Brazil,
and Russia.
The fourth Congress was held October 26 to 28, 1909, in Billings,
Montana, under the presidency of Governor Edwin L. Morris of
Montana. The uncertain weather of the winter months had led the
previous Congress to adopt a time in the autumn as the date of the
annual meeting. This Congress became a session at which many of the
principles discussed during the three preceding Congresses were
crystallized into definite statements and agreed upon by workers
from various parts of the country. A number of foreign
representatives were present again. The problems of the Northwest
and Canada were given special attention. The attendance was larger
than at any of the preceding Congresses.
The fifth Congress will be held under the presidency of Hon. F. W.
Mondell of Wyoming at Spokane, Washington, during October, 1910. It
promises to exceed any preceding Congress in attendance and
interest.
The Dry-farming Congress has made itself one of the most important
factors in the development of methods for the reclamation of the
desert. Its published reports are the most valuable publications
dealing with dry-land agriculture. Only simple justice is done when
it is stated that the success of the Dry-farming Congress is due in
a large measure to the untiring and intelligent efforts of John T.
Burns, who is the permanent secretary of the Congress, and who was a
member of the first executive committee.
Nearly all the arid and semiarid states have organized state
dry-farming congresses. The first of these was the Utah Dry-farming
Congress, organized about two months after the first Congress held
in Denver. The president is L. A. Merrill, one of the pioneer
dry-farm investigators of the Rockies.
Jethro Tull (see frontispiece)
A sketch of the history of dry-farming would be incomplete without a
mention of the life and work of Jethro Tull. The agricultural
doctrines of this man, interpreted in the light of modern science,
are those which underlie modern dry-farming. Jethro Tull was born in
Berkshire, England, 1674, and died in 1741. He was a lawyer by
profession, but his health was so poor that he could not practice
his profession and therefore spent most of his life in the seclusion
of a quiet farm. His life work was done in the face of great
physical sufferings. In spite of physical infirmities, he produced a
system of agriculture which, viewed in the light of our modern
knowledge, is little short of marvelous. The chief inspiration of
his system came from a visit paid to south of France, where he
observed "near Frontignan and Setts, Languedoc" that the vineyards
were carefully plowed and tilled in order to produce the largest
crops of the best grapes. Upon the basis of this observation he
instituted experiments upon his own farm and finally developed his
system, which may be summarized as follows: The amount of seed to be
used should be proportional to the condition of the land, especially
to the moisture that is in it. To make the germination certain, the
seed should be sown by drill methods. Tull, as has already been
observed, was the inventor of the seed drill which is now a feature
of all modern agriculture. Plowing should be done deeply and
frequently; two plowings for one crop would do no injury and
frequently would result in an increased yield. Finally, as the most
important principle of the system, the soil should be cultivated
continually, the argument being that by continuous cultivation the
fertility of the soil would be increased, the water would be
conserved, and as the soil became more fertile less water would be
used. To accomplish such cultivation, all crops should be placed in
rows rather far apart, so far indeed that a horse carrying a
cultivator could walk between them. The horse-hoeing idea of the
system became fundamental and gave the name to his famous book, "The
Horse Hoeing Husbandry," by Jethro Tull, published in parts from
1731 to 1741. Tull held that the soil between the rows was
essentially being fallowed and that the next year the seed could be
planted between the rows of the preceding year and in that way the
fertility could be maintained almost indefinitely. If this method
were not followed, half of the soil could lie fallow every other
year and be subjected to continuous cultivation. Weeds consume water
and fertility and, therefore, fallowing and all the culture must be
perfectly clean. To maintain fertility a rotation of crops should be
practiced. Wheat should be the main grain crop; turnips the root
crop; and alfalfa a very desirable crop.
It may be observed that these teachings are sound and in harmony
with the best knowledge of to-day and that they are the very
practices which are now being advocated in all dry-farm sections.
This is doubly curious because Tull lived in a humid country.
However, it may be mentioned that his farm consisted of a very poor
chalk soil, so that the conditions under which he labored were more
nearly those of an arid country than could ordinarily be found in a
country of abundant rainfall. While the practices of Jethro Tull
were in themselves very good and in general can be adopted to-day,
yet his interpretation of the principles involved was wrong. In view
of the limited knowledge of his day, this was only to be expected.
For instance, he believed so thoroughly in the value of cultivation
of the soil, that he thought it would take the place of all other
methods of maintaining soil-fertility. In fact, he declared
distinctly that "tillage is manure," which we are very certain at
this time is fallacious. Jethro Tull is one of the great
investigators of the world. In recognition of the fact that, though
living two hundred years ago in a humid country, he was able to
develop the fundamental practices of soil culture now used in
dry-farming, the honor has been done his memory of placing his
portrait as the frontispiece of this volume.
CHAPTER XX
DRY-FARMING IN A NUTSHELL
Locate the dry-farm in a section with an annual precipitation of
more than ten inches and, if possible, with small wind movement. One
man with four horses and plenty of machinery cannot handle more than
from 160 to 200 acres. Farm fewer acres and farm them better.
Select a clay loam soil. Other soils may be equally productive, but
are cultivated properly with somewhat more difficulty.
Make sure, with the help of the soil auger, that the soil is of
uniform structure to a depth of at least eight feet. If streaks of
loose gravel or layers of hardpan are near the surface, water may be
lost to the plant roots.
After the land has been cleared and broken let it lie fallow with
clean cultivation, for one year. The increase in the first and later
crops will pay for the waiting.
Always plow the land early in the fall, unless abundant experience
shows that fall plowing is an unwise practice in the locality.
Always plow deeply unless the subsoil is infertile, in which case
plow a little deeper each year until eight or ten inches are reached
Plow at least once for each crop. Spring plowing; if practiced,
should be done as early as possible in the season.
Follow the plow, whether in the fall or spring, with the disk and
that with the smoothing harrow, if crops are to be sown soon
afterward. If the land plowed in the fall is to lie fallow for the
winter, leave it in the rough condition, except in localities where
there is little or no snow and the winter temperature is high.
Always disk the land in early spring, to prevent evaporation. Follow
the disk with the harrow. Harrow, or in some other way stir the
surface of the soil after every rain. If crops are on the land,
harrow as long as the plants will stand it. If hoed crops, like corn
or potatoes, are grown, use the cultivator throughout the season. A
deep mulch or dry soil should cover the land as far as possible
throughout the summer. Immediately after harvest disk the soil
thoroughly.
Destroy weeds as soon as they show themselves. A weedy dry-farm is
doomed to failure.
Give the land an occasional rest, that is, a clean summer fallow.
Under a rainfall of less than fifteen inches, the land should be
summer fallowed every other year; under an annual rainfall of
fifteen to twenty inches, the summer fallow should occur every third
or fourth year. Where the rainfall comes chiefly in the summer, the
summer fallow is less important in ordinary years than where the
summers are dry and the winters wet. Only an absolutely clean fallow
should be permitted.
The fertility of dry-farm soils must be maintained. Return the
manure; plow under green leguminous crops occasionally and practice
rotation. On fertile soils plants mature with the least water.
Sow only by the drill method. Wherever possible use fall varieties
of crops. Plant deeply--three or four inches for grain. Plant early
in the fall, especially if the land has been summer fallowed. Use
only about one half as much seed as is recommended for
humid-farming.
All the ordinary crops may be grown by dry-farming. Secure seed that
has been raised on dry-farms. Look out for new varieties, especially
adapted for dry-farming, that may be brought in. Wheat is king in
dry-farming; corn a close second. Turkey wheat promises the best.
Stock the dry-farm with the best modern machinery. Dry-farming is
possible only because of the modern plow, the disk, the drill
seeder, the harvester, the header, and the thresher.
Make a home on the dry-farm. Store the flood waters in a reservoir;
or pump the underground waters, for irrigating the family garden.
Set out trees, plant flowers, and keep some live stock.
Learn to understand the reasons back of the principles of
dry-farming, apply the knowledge vigorously, and the crop cannot
fail.
Always farm as if a year of drouth were coming.
Man, by his intelligence, compels the laws of nature to do his
bidding, and thus he achieves joy.
"And God blessed them--and God said unto them, Be fruitful and
multiply and replenish the earth, and subdue it."
CHAPTER XIX
THE YEAR OF DROUTH
The Shadow of the Year of Drouth still obscures the hope of many a
dry-farmer. From the magazine page and the public platform the
prophet of evil, thinking himself a friend of humanity, solemnly
warns against the arid region and dry-farming, for the year of
drouth, he says, is sure to come again and then will be repeated the
disasters of 1893-1895. Beware of the year of drouth. Even
successful dry-farmers who have obtained good crops every year for a
generation or more are half led to expect a dry year or one so dry
that crops will fail in spite of all human effort. The question is
continually asked, "Can crop yields reasonably be expected every
year, through a succession of dry years, under semiarid conditions,
if the best methods of dry-farming be practiced?" In answering this
question, it may be said at the very beginning, that when the year
of drouth is mentioned in connection with dry-farming, sad reference
is always made to the experience on the Great Plains in the early
years of the '90's. Now the fact of the matter is, that while the
years of 1893,1894, and 1895 were dry years, the only complete
failure came in 1894. In spite of the improper methods practiced by
the settlers, the willing soil failed to yield a crop only one year.
Moreover, it should not be forgotten that hundreds of farmers in the
driest section during this dry period, who instinctively or
otherwise farmed more nearly right, obtained good crops even in
1894. The simple practice of summer fallowing, had it been practiced
the year before, would have insured satisfactory crops in the driest
year. Further, the settlers who did not take to their heels upon the
arrival of the dry year are still living in large numbers on their
homesteads and in numerous instances have accumulated comfortable
fortunes from the land which has been held up so long as a warning
against settlement beyond a humid climate. The failure of 1894 was
due as much to a lack of proper agricultural information and
practice as to the occurrence of a dry year.
Next, the statement is carelessly made that the recent success in
dry-farming is due to the fact that we are now living in a cycle of
wet years, but that as soon as the cycle of dry years strikes the
country dry-farming will vanish as a dismal failure. Then, again,
the theory is proposed that the climate is permanently changing
toward wetness or dryness and the past has no meaning in reading the
riddle of the future. It is doubtless true that no man may safely
predict the weather for future generations; yet, so far as human
knowledge goes, there is no perceptible average change in the
climate from period to period within historical time; neither are
there protracted dry periods followed by protracted wet periods. The
fact is, dry and wet years alternate. A succession of somewhat wet
years may alternate with a succession of somewhat dry years, but the
average precipitation from decade to decade is very nearly the same.
True, there will always be a dry year, that is, the driest year of a
series of years, and this is the supposedly fearful and fateful year
of drouth. The business of the dry-farmer is always to farm so as to
be prepared for this driest year whenever it comes. If this be done,
the farmer will always have a crop: in the wet years his crop will
be large; in the driest year it will be sufficient to sustain him.
So persistent is the half-expressed fear that this driest year makes
it impossible to rely upon dry-farming as a permanent system of
agriculture that a search has been made for reliable long records of
the production of crops in arid and semiarid regions. Public
statements have been made by many perfectly reliable men to the
effect that crops have been produced in diverse sections over long
periods of years, some as long as thirty-five or forty year's,
without one failure having occurred. Most of these statements,
however, have been general in their nature and not accompanied by
the exact yields from year to year. Only three satisfactory records
have been found in a somewhat careful search. Others no doubt exist.
The first record was made by Senator J. G. M. Barnes of Kaysville,
Utah. Kaysville is located in the Great Salt Lake Valley, about
fifteen miles north of Salt Lake City. The climate is semiarid; the
precipitation comes mainly in the winter and early spring; the
summers are dry, and the evaporation is large. Senator Barnes
purchased ninety acres of land in the spring of 1887 and had it
farmed under his own supervision until 1906. He is engaged in
commercial enterprises and did not, himself, do any of the work on
the farm, but employed men to do the necessary labor. However, he
kept a close supervision of the farm and decided upon the practices
which should be followed. From seventy-eight to eighty-nine acres
were harvested for each crop, with the exception of 1902, when all
but about twenty acres was fired by sparks from the passing railroad
train. The plowing, harrowing, and weeding were done very carefully.
The complete record of the Barnes dry-farm from 1887 to 1905 is
shown in the table on the following page.
Record of the Barnes Dry-farm, Salt Lake Valley, Utah (90 acres)
Year Annual Yield When When
Rainfall per Acre Plowed Sown
(Inches) (Bu.)
1887 11.66 --- May Sept.
1888 13.62 Failure May Sept.
1889 18.46 22.5 --- Volunteer+
1890 10.38 15.5 --- ---
1891 15.92 Fallow May Fall
1892 14.08 19.3 --- ---
1893 17.35 Fallow May Fall
1894 15.27 26.0 --- ---
1895 11.95 Fallow May Aug.
1896 18.42 22.0 --- ---
1897 16.74 Fallow Spring Fall
1898 16.09 26.0 --- ---
1899 17.57 Fallow May Fall
1900 11.53 23.5 --- ---
1901 16.08 Fallow Spring Fall
1902 11.41 28.9 Sept. Fall
1903 14.62 12.5 --- ---
1904 16.31 Fallow Spring Fall
1905 14.23 25.8 --- ---
+About four acres were sown on stubble.
The first plowing was given the farm in May of 1887, and, with the
exception of 1902, the land was invariably plowed in the spring.
With fall plowing the yields would undoubtedly have been better. The
first sowing was made in the fall of 1887, and fall grain was grown
during the whole period of observation. The seed sown in the fall of
1887 came up well, but was winter-killed. This is ascribed by
Senator Barnes to the very dry winter, though it is probable that
the soil was not sufficiently well stored with moisture to carry the
crop through. The farm was plowed again in the spring of 1888, and
another crop sown in September of the same year. In the summer of
1889, 22-1/2 bushels of wheat were harvested to the acre. Encouraged
by this good crop Mr. Barnes allowed a volunteer crop to grow that
fall and the next summer harvested as a result 15-1/2 bushels of
wheat to the acre. The table shows that only one crop smaller than
this was harvested during the whole period of nineteen years,
namely, in 1903, when the same thing was done, and one crop was made
to follow another without an intervening fallow period. This
observation is an evidence in favor of clean summer fallowing. The
largest crop obtained, 28.9 bushels per acre in 1902, was gathered
in a year when the next to the lowest rainfall of the whole period
occurred, namely, 11.41 inches.
The precipitation varied during the nineteen years from 10.33 inches
to 18.46 inches. The variation in yield per acre was considerably
less than this, not counting the two crops that were grown
immediately after another crop. All in all, the unique record of the
Barnes dry-farm shows that through a period of nineteen years,
including dry and comparatively wet years, there was absolutely no
sign of failure, except in the first year, when probably the soil
had not been put in proper condition to support crops. In passing it
maybe mentioned that, according to the records furnished by Senator
Barnes, the total cost of operating the farm during the nineteen
years was $4887.69; the total income was $10,144.83. The difference,
$5257.14, is a very fair profit on the investment of $1800--the
original cost of the farm.
The Indian Head farm
An equally instructive record is furnished by the experimental farm
located at Indian Head in Saskatchewan, Canada, in the northern part
of the Great Plains area. According to Alway, the country is in
appearance very much like western Nebraska and Kansas; the climate
is distinctly arid, and the precipitation comes mainly in the spring
and summer. It is the only experimental dry-farm in the Great Plains
area with records that go back before the dry years of the early
'90's. In 1882 the soil of this farm was broken, and it was farmed
continuously until 1888, when it was made an experimental farm under
government supervision. The following table shows the yields
obtained from the year 1891, when the precipitation records were
first kept, to 1909:--
RECORD OF INDIAN HEAD EXPERIMENTAL FARM AND MOTHERWELL'S FARM,
SASKATCHEWAN, CANADA
Year Annual Bushels of Wheat Bushels of Wheat Bushels of Wheat
Rainfall per Acre per Acre per Acre
(Inches)+ Experimental Experimental Motherwell's Farm
Farm--Fallow Farm--Stubble
1891 14.03 35 32 30
1892 6.92 28 21 28
1893 10.11 35 22 34
1894 3.90 17 9 24
1895 12.28 41 22 26
1896 10.59 39 29 31
1897 14.62 33 26 35
1898 18.03 32 --- 27
1899 9.44 33 --- 33
1900 11.74 17 5 25
1901 20.22 49 38 51
1902 10.73 38 22 28
1903 15.55 35 15 31
1904 11.96 40 29 35
1905 19.17 42 18 36
1906 13.21 26 13 38
1907 15.03 18 18 15
1908 13.17 29 14 16
1909 13.96 28 15 23
+Snowfall not included. This has varied from 2.3 to 1.3 inches of water.
The annual rainfall shown in the second column does not include the
water which fell in the form of snow. According to the records at
hand, the annual snow fall varied from 2.3 to 1.3 inches of water,
which should be added to the rainfall given in the table. Even with
this addition the rainfall shows the district to be of a distinctly
semiarid character. It will be observed that the precipitation
varied from 3.9 to 20.22 inches, and that during the early '90's
several rather dry years occurred. In spite of this large variation
good crops have been obtained during the whole period of nineteen
years. Not one failure is recorded. The lowest yield of 17 bushels
per acre came during the very dry year of 1894 and during the
somewhat dry year of 1900. Some of the largest yields were obtained
in seasons when the rainfall was only near the average. As a record
showing that the year of drouth need not be feared when dry-farming
is done right, this table is of very high interest. It may be noted,
incidentally, that throughout the whole period wheat following a
fallow always yielded higher than wheat following the stubble. For
the nineteen years, the difference was as 32.4 bushels is to 20.5
bushels.
The Mother well farm
In the last column of the table are shown the annual yields of wheat
obtained on the farm of Commissioner Motherwell of the province of
Saskatchewan. This private farm is located some twenty-five miles
away from Indian Head, and the rainfall records of the experimental
farm are, therefore, only approximately accurate for the Motherwell
farm. The results on this farm may well be compared to the Barnes
results of Utah, since they were obtained on a private farm. During
the period of nineteen years good crops were invariably obtained;
even during the very dry year of 1894, a yield of twenty-four
bushels of wheat to the acre was obtained. Curiously enough, the
lowest yields of fifteen and sixteen bushels to the acre were
obtained in 1907 and 1908 when the precipitation was fairly good,
and must be ascribed to some other factor than that of
precipitation. The record of this farm shows conclusively that with
proper farming there is no need to fear the year of drouth.
The Utah drouth of 1910
During the year of 1910 only 2.7 inches of rain fell in Salt Lake
City from March 1 to the July harvest, and all of this in March, as
against 7.18 inches during the same period the preceding year. In
other parts of the state much less rain fell; in fact, in the
southern part of the state the last rain fell during the last week
of December, 1909. The drouth remained unbroken until long after the
wheat harvests. Great fear was expressed that the dry-farms could
not survive so protracted a period of drouth. Agents, sent out over
the various dry-farm districts, reported late in June that wherever
clean summer fallowing had been practiced the crops were in
excellent condition; but that wherever careless methods had been
practiced, the crops were poor or killed. The reports of the harvest
in July of 1910 showed that fully 85 per cent of an average crop was
obtained in spite of the protracted drouth wherever the soil came
into the spring well stored with moisture, and in many instances
full crops were obtained.
Over the whole of the dry-farm territory of the United States
similar conditions of drouth occurred. After the harvest, however,
every state reported that the crops were well up to the average
wherever correct methods of culture had been employed.
These well-authenticated records from true semi-arid districts,
covering the two chief types of winter and summer precipitation,
prove that the year of drouth, or the driest year in a twenty-year
period, does not disturb agricultural conditions seriously in
localities where the average annual precipitation is not too low,
and where proper cultural methods arc followed. That dry-farming is
a system of agricultural practice which requires the application of
high skill and intelligence is admitted; that it is precarious is
denied. The year of drouth is ordinarily the year in which the man
failed to do properly his share of the work.
CHAPTER XVIII
THE PRESENT STATUS OF DRY-FARMING
It is difficult to obtain a correct view of the present status of
dry-farming, first, because dry-farm surveys are only beginning to
be made and, secondly, because the area under dry-farm cultivation
is increasing daily by leaps and bounds. All arid and semiarid parts
of the world are reaching out after methods of soil culture whereby
profitable crops may be produced without irrigation, and the
practice of dry-farming, according to modern methods, is now
followed in many diverse countries. The United States undoubtedly
leads at present in the area actually under dry-farming, but, in
view of the immense dry-farm districts in other parts of the world,
it is doubtful if the United States will always maintain its
supremacy in dry-farm acreage. The leadership in the development of
a science of dry-farming will probably remain with the United States
for years, since the numerous experiment stations established for
the study of the problems of farming without irrigation have their
work well under way, while, with the exception of one or two
stations in Russia and Canada, no other countries have experiment
stations for the study of dry-farming in full operation. The reports
of the Dry-farming Congress furnish practically the only general
information as to the status of dry-farming in the states and
territories of the United States and in the countries of the world.
California
In the state of California dry-farming has been firmly established
for more than a generation. The chief crop of the California
dry-farms is wheat, though the other grains, root crops, and
vegetables are also grown without irrigation under a comparatively
small rainfall. The chief dry-farm areas are found in the Sacramento
and the San Joaquin valleys. In the Sacramento Valley the
precipitation is fairly large, but in the San Joaquin Valley it is
very small. Some of the most successful dry-farms of California have
produced well for a long succession of years under a rainfall of ten
inches and less. California offers a splendid example of the great
danger that besets all dry-farm sections. For a generation wheat has
been produced on the fertile Californian soils without manuring of
any kind. As a consequence, the fertility of the soils has been so
far depleted that at present it is difficult to obtain paying crops
without irrigation on soils that formerly yielded bountifully. The
living problem of the dry-farms in California is the restoration of
the fertility which has been removed from the soils by unwise
cropping. All other dry-farm districts should take to heart this
lesson, for, though crops may be produced on fertile soils for one,
two, or even three generations without manuring, yet the time will
come when plant-food must be added to the soil in return for that
which has been removed by the crops. Meanwhile, California offers,
also, an excellent example of the possibility of successful
dry-farming through long periods and under varying climatic
conditions. In the Golden State dry-farming is a fully established
practice; it has long since passed the experimental stage.
Columbia River Basin
The Columbia River Basin includes the state of Washington, most of
Oregon, the northern and central part of Idaho, western Montana, and
extends into British Columbia. It includes the section often called
the Inland Empire, which alone covers some one hundred and fifty
thousand square miles. The chief dry-farm crop of this region is
wheat; in fact, western Washington or the "Palouse country" is
famous for its wheat-producing powers. The other grains, potatoes,
roots, and vegetables are also grown without irrigation. In the
parts of this dry-farm district where the rainfall is the highest,
fruits of many kinds and of a high quality are grown without
irrigation. It is estimated that at least two million acres are
being dry-farmed in this district. Dry-farming is fully established
in the Columbia River Basin. One farmer is reported to have raised
in one year on his own farm two hundred and fifty thousand bushels
of wheat. In one section of the district where the rainfall for the
last few years has been only about ten or eleven inches, wheat has
been produced successfully. This corroborates the experience of
California, that wheat may really be grown in localities where the
annual rainfall is not above ten inches. The most modern methods of
dry-farming are followed by the farmers of the Columbia River Basin,
but little attention has been given to soil-fertility, since soils
that have been farmed for a generation still appear to retain their
high productive powers. Undoubtedly, however, in this district, as
in California, the question of soil-fertility will be an important
one in the near future. This is one of the great dry-farm districts
of the world.
The Great Basin
The Great Basin includes Nevada, the western half of Utah, a small
part of southern Oregon and Idaho, and also a part of Southern
California. It is a great interior basin with all its rivers
draining into salt lakes or dry sinks. In recent geological times
the Great Basin was filled with water, forming the great Lake
Bonneville which drained into the Columbia River. In fact, the Great
Basin is made up of a series of great valleys, with very level
floors, representing the old lake bottom. On the bench lands are
seen, in many places, the effects of the wave action of the ancient
lake. The chief dry-farm crop of this district is wheat, but the
other grains, including corn, are also produced successfully. Other
crops have been tried with fair success, but not on a commercial
scale. Grapevines have been made to grow quite successfully without
irrigation on the bench lands. Several small orchards bearing
luscious fruit are growing on the deep soils of the Great Basin
without the artificial application of water. Though the first
dry-farming by modern peoples was probably practiced in the Great
Basin, yet the area at present under cultivation is not large,
possibly a little more than four hundred thousand acres.
Dry-farming, however, is well established. There are large areas,
especially in Nevada, that receive less than ten inches of rainfall
annually, and one of the leading problems before the dry-farmers of
this district is the determination of the possibility of producing
crops upon such lands without irrigation. On the older dry-farms,
which have existed in some cases from forty to fifty years, there
are no signs of diminution of soil-fertility. Undoubtedly, however,
even under the conditions of extremely high fertility prevailing in
the Great Basin, the time will soon come when the dry-farmer must
make provision for restoring to the soil some of the fertility taken
away by crops. There are millions of acres in the Great Basin yet to
be taken up and subjected to the will of the dry-farmer.
Colorado and Rio Grande River Basins
The Colorado and Rio Grande River Basins include Arizona and the
western part of New Mexico. The chief dry-farm crops of this dry
district are wheat, corn, and beans. Other crops have also been
grown in small quantities and with some success. The area suitable
for dry-farming in this district has not yet been fully determined
and, therefore, the Arizona and New Mexico stations are undertaking
dry-farm surveys of their respective states. In spite of the fact
that Arizona is generally looked upon as one of the driest states of
the Union, dry-farming is making considerable headway there. In New
Mexico, five sixths of all the homestead applications during the
last year were for dry-farm lands; and, in fact, there are several
prosperous communities in New Mexico which are subsisting almost
wholly on dry-farming. It is only fair to say, however, that
dry-farming is not yet well established in this district, but that
the prospects are that the application of scientific principles will
soon make it possible to produce profitable crops without irrigation
in large parts of the Colorado and Rio Grande River Basins.
The mountain states
This district includes a part of Montana, nearly the whole of
Wyoming and Colorado, and part of eastern Idaho. It is located along
the backbone of the Rocky Mountains. The farms are located chiefly
in valleys and on large rolling table-lands. The chief dry-farm crop
is wheat, though the other crops which are grown elsewhere on
dry-farms may be grown here also. In Montana there is a very large
area of land which has been demonstrated to be well adapted for
dry-farm purposes. In Wyoming, especially on the eastern as well as
on the far western side, dry-farming has been shown to be
successful, but the area covered at the present time is
comparatively small. In Idaho, dry-farming is fairly well
established. In Colorado, likewise, the practice is very well
established and the area is tolerably large. All in all, throughout
the mountain states dry-farming may be said to be well established,
though there is a great opportunity for the extension of the
practice. The sparse population of the western states naturally
makes it impossible for more than a small fraction of the land to be
properly cultivated.
The Great Plains Area
This area includes parts of Montana, North Dakota, South Dakota,
Nebraska, Kansas, Wyoming, Colorado, New Mexico, Oklahoma, and
Texas. It is the largest area of dry-farm land under approximately
uniform conditions. Its drainage is into the Mississippi, and it
covers an area of not less than four hundred thousand square miles.
Dry-farm crops grow well over the whole area; in fact, dry-farming
is well established in this district. In spite of the failures so
widely advertised during the dry season of 1894, the farmers who
remained on their farms and since that time have employed modern
methods have secured wealth from their labors. The important
question before the farmers of this district is that of methods for
securing the best results. From the Dakotas to Texas the farmers
bear the testimony that wherever the soil has been treated right,
according to approved methods, there have been no crop failures.
Canada
Dry-farming has been pushed vigorously in the semiarid portions of
Canada, and with great success. Dry-farming is now reclaiming large
areas of formerly worthless land, especially in Alberta,
Saskatchewan, and the adjoining provinces. Dry-farming is
comparatively recent in Canada, yet here and there are semiarid
localities where crops have been raised without irrigation for
upwards of a quarter of a century. In Alberta and other places it
has been now practiced successfully for eight or ten years, and it
may be said that dry-farming is a well-established practice in the
semiarid regions of the Dominion of Canada.
Mexico
In Mexico, likewise, dry-farming has been tried and found to be
successful. The natives of Mexico have practiced farming without
irrigation for centuries--and modern methods are now being applied
in the zone midway between the extremely dry and the extremely humid
portions. The irregular distribution of the precipitation, the late
spring and early fall frosts, and the fierce winds combine to make
the dry-farm problem somewhat difficult, yet the prospects are that,
with government assistance, dry-farming in the near future will
become an established practice in Mexico. In the opinion of the best
students of Mexico it is the only method of agriculture that can be
made to reclaim a very large portion of the country.
Brazil
Brazil, which is greater in area than the United States, also has a
large arid and semiarid territory which can be reclaimed only by
dry-farm methods. Through the activity of leading citizens
experiments in behalf of the dry-farm movement have already been
ordered. The dry-farm district of Brazil receives an annual
precipitation of about twenty-five inches, but irregularly
distributed and under a tropical sun. In the opinion of those who
are familiar with the conditions the methods of dry-farming may be
so adapted as to make dry-farming successful in Brazil.
Australia
Australia, larger than the continental United States, is vitally
interested in dry-farming, for one third of its vast area is under a
rainfall of less than ten inches, and another third is under a
rainfall of between ten and twenty inches. Two thirds of the area of
Australia, if reclaimed at all, must be reclaimed by dry-farming.
The realization of this condition has led several Australians to
visit the United States for the purpose of learning the methods
employed in dry-farming. The reports on dry-farming in America by
Surveyor-General Strawbridge and Senator J. H. McColl have done much
to initiate a vigorous propaganda in behalf of dry-farming in
Australia. Investigation has shown that occasional farmers are found
in Australia, as in America, who have discovered for themselves many
of the methods of dry-farming and have succeeded in producing crops
profitably. Undoubtedly, in time, Australia will be one of the great
dry-farming countries of the world.
Africa
Up to the present, South Africa only has taken an active interest in
the dry-farm movement, due to the enthusiastic labors of Dr. William
Macdonald of the Transvaal. The Transvaal has an average annual
precipitation of twenty-three inches, with a large district that
receives between thirteen and twenty inches. The rain comes in the
summer, making the conditions similar to those of the Great Plains.
The success of dry-farming has already been practically
demonstrated. The question before the Transvaal farmers is the
determination of the best application of water conserving methods
under the prevailing conditions. Under proper leadership the
Transvaal and other portions of Africa will probably join the ranks
of the larger dry-farming countries of the world.
Russia
More than one fourth of the whole of Russia is so dry as to be
reclaimable only by dry-farming. The arid area of southern European
Russia has a climate very much like that of the Great Plains.
Turkestan and middle Asiatic Russia have a climate more like that of
the Great Basin. In a great number of localities in both European
and Asiatic Russia dry-farming has been practiced for a number of
years. The methods employed have not been of the most refined kind,
due, possibly, to the condition of the people constituting the
farming class. The government is now becoming interested in the
matter and there is no doubt that dry-farming will also be practiced
on a very large scale in Russia.
Turkey
Turkey has also a large area of arid land and, due to American
assistance, experiments in dry-farming are being carried on in
various parts of the country. It is interesting to learn that the
experiments there, up to date, have been eminently successful and
that the prospects now are that modern dry-farming will soon be
conducted on a large scale in the Ottoman Empire.
Palestine
The whole of Palestine is essentially arid and semi-arid and
dry-farming there has been practiced for centuries. With the
application of modern methods it should be more successful than ever
before. Dr. Aaronsohn states that the original wild wheat from which
the present varieties of wheat have descended has been discovered to
be a native of Palestine.
China
China is also interested in dry-farming. The climate of the drier
portions of China is much like that of the Dakotas. Dry-farming
there is of high antiquity, though, of course, the methods are not
those that have been developed in recent years. Under the influence
of the more modern methods dry-farming should spread extensively
throughout China and become a great source of profit to the empire.
The results of dry-farming in China are among the best.
These countries have been mentioned simply because they have been
represented at the recent Dry-farming Congresses. Nearly all of the
great countries of the world having extensive semiarid areas are
directly interested in dry-farming. The map on pages 30 and 31 shows
that more than 55 per cent of the world's surface receives an annual
rainfall of less than twenty inches. Dry-farming is a world problem
and as such is being received by the nations.
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